diff --git a/framework/src/Volo.Abp.MemoryDb/Volo/Abp/Domain/Repositories/MemoryDb/IMemoryDatabase.cs b/framework/src/Volo.Abp.MemoryDb/Volo/Abp/Domain/Repositories/MemoryDb/IMemoryDatabase.cs
index 1e6cd6f54c..9f2bf33a40 100644
--- a/framework/src/Volo.Abp.MemoryDb/Volo/Abp/Domain/Repositories/MemoryDb/IMemoryDatabase.cs
+++ b/framework/src/Volo.Abp.MemoryDb/Volo/Abp/Domain/Repositories/MemoryDb/IMemoryDatabase.cs
@@ -1,10 +1,10 @@
-using System.Collections.Generic;
+using Volo.Abp.Domain.Entities;
 
 namespace Volo.Abp.Domain.Repositories.MemoryDb
 {
     public interface IMemoryDatabase
     {
-        List<TEntity> Collection<TEntity>();
+        IMemoryDatabaseCollection<TEntity> Collection<TEntity>() where TEntity : class, IEntity;
 
         TKey GenerateNextId<TEntity, TKey>();
     }
diff --git a/framework/src/Volo.Abp.MemoryDb/Volo/Abp/Domain/Repositories/MemoryDb/IMemoryDatabaseCollection.cs b/framework/src/Volo.Abp.MemoryDb/Volo/Abp/Domain/Repositories/MemoryDb/IMemoryDatabaseCollection.cs
new file mode 100644
index 0000000000..f730bbbe48
--- /dev/null
+++ b/framework/src/Volo.Abp.MemoryDb/Volo/Abp/Domain/Repositories/MemoryDb/IMemoryDatabaseCollection.cs
@@ -0,0 +1,15 @@
+using System.Collections.Generic;
+
+namespace Volo.Abp.Domain.Repositories.MemoryDb
+{
+    public interface IMemoryDatabaseCollection<TEntity> : IEnumerable<TEntity>
+    {
+        void Add(TEntity entity);
+
+        void Update(TEntity entity);
+
+        void Remove(TEntity entity);
+
+        bool Contains(TEntity entity);
+    }
+}
\ No newline at end of file
diff --git a/framework/src/Volo.Abp.MemoryDb/Volo/Abp/Domain/Repositories/MemoryDb/IMemoryDbRepository.cs b/framework/src/Volo.Abp.MemoryDb/Volo/Abp/Domain/Repositories/MemoryDb/IMemoryDbRepository.cs
index dd241b25a5..c179b68931 100644
--- a/framework/src/Volo.Abp.MemoryDb/Volo/Abp/Domain/Repositories/MemoryDb/IMemoryDbRepository.cs
+++ b/framework/src/Volo.Abp.MemoryDb/Volo/Abp/Domain/Repositories/MemoryDb/IMemoryDbRepository.cs
@@ -8,7 +8,7 @@ namespace Volo.Abp.Domain.Repositories.MemoryDb
     {
         IMemoryDatabase Database { get; }
 
-        List<TEntity> Collection { get; }
+        IMemoryDatabaseCollection<TEntity> Collection { get; }
     }
 
     public interface IMemoryDbRepository<TEntity, TKey> : IMemoryDbRepository<TEntity>, IRepository<TEntity, TKey>
diff --git a/framework/src/Volo.Abp.MemoryDb/Volo/Abp/Domain/Repositories/MemoryDb/IMemoryDbSerializer.cs b/framework/src/Volo.Abp.MemoryDb/Volo/Abp/Domain/Repositories/MemoryDb/IMemoryDbSerializer.cs
new file mode 100644
index 0000000000..8dec50fb75
--- /dev/null
+++ b/framework/src/Volo.Abp.MemoryDb/Volo/Abp/Domain/Repositories/MemoryDb/IMemoryDbSerializer.cs
@@ -0,0 +1,9 @@
+namespace Volo.Abp.Domain.Repositories.MemoryDb
+{
+    public interface IMemoryDbSerializer
+    {
+        object Serialize(object obj);
+
+        object Deserialize(object obj);
+    }
+}
\ No newline at end of file
diff --git a/framework/src/Volo.Abp.MemoryDb/Volo/Abp/Domain/Repositories/MemoryDb/MemoryDatabase.cs b/framework/src/Volo.Abp.MemoryDb/Volo/Abp/Domain/Repositories/MemoryDb/MemoryDatabase.cs
index be16beef85..1df0397869 100644
--- a/framework/src/Volo.Abp.MemoryDb/Volo/Abp/Domain/Repositories/MemoryDb/MemoryDatabase.cs
+++ b/framework/src/Volo.Abp.MemoryDb/Volo/Abp/Domain/Repositories/MemoryDb/MemoryDatabase.cs
@@ -1,6 +1,7 @@
-using System;
+using System;
 using System.Collections.Concurrent;
 using System.Collections.Generic;
+using Volo.Abp.Domain.Entities;
 
 namespace Volo.Abp.Domain.Repositories.MemoryDb
 {
@@ -16,9 +17,12 @@ namespace Volo.Abp.Domain.Repositories.MemoryDb
             _entityIdGenerators = new ConcurrentDictionary<Type, InMemoryIdGenerator>();
         }
 
-        public List<TEntity> Collection<TEntity>()
+        public IMemoryDatabaseCollection<TEntity> Collection<TEntity>()
+            where TEntity : class, IEntity
         {
-            return _sets.GetOrAdd(typeof(TEntity), _ => new List<TEntity>()) as List<TEntity>;
+            return _sets.GetOrAdd(typeof(TEntity),
+                    _ => new MemoryDatabaseCollection<TEntity>(new MemoryDbBinarySerializer())) as
+                MemoryDatabaseCollection<TEntity>;
         }
 
         public TKey GenerateNextId<TEntity, TKey>()
diff --git a/framework/src/Volo.Abp.MemoryDb/Volo/Abp/Domain/Repositories/MemoryDb/MemoryDatabaseCollection.cs b/framework/src/Volo.Abp.MemoryDb/Volo/Abp/Domain/Repositories/MemoryDb/MemoryDatabaseCollection.cs
new file mode 100644
index 0000000000..d7d77ce6f4
--- /dev/null
+++ b/framework/src/Volo.Abp.MemoryDb/Volo/Abp/Domain/Repositories/MemoryDb/MemoryDatabaseCollection.cs
@@ -0,0 +1,61 @@
+using System;
+using System.Collections;
+using System.Collections.Generic;
+using Volo.Abp.Domain.Entities;
+
+namespace Volo.Abp.Domain.Repositories.MemoryDb
+{
+    public class MemoryDatabaseCollection<TEntity> : IMemoryDatabaseCollection<TEntity>
+        where TEntity : class, IEntity
+    {
+        private readonly Dictionary<string, object> _dictionary = new Dictionary<string, object>();
+
+        private readonly IMemoryDbSerializer _memoryDbSerializer;
+
+        public MemoryDatabaseCollection(IMemoryDbSerializer memoryDbSerializer)
+        {
+            _memoryDbSerializer = memoryDbSerializer;
+        }
+
+        public IEnumerator<TEntity> GetEnumerator()
+        {
+            foreach (var entity in _dictionary.Values)
+            {
+                yield return _memoryDbSerializer.Deserialize(entity).As<TEntity>();
+            }
+        }
+
+        IEnumerator IEnumerable.GetEnumerator()
+        {
+            return GetEnumerator();
+        }
+
+        public void Add(TEntity entity)
+        {
+            _dictionary.Add(GetEntityKey(entity), _memoryDbSerializer.Serialize(entity));
+        }
+
+        public void Update(TEntity entity)
+        {
+            if (_dictionary.ContainsKey(GetEntityKey(entity)))
+            {
+                _dictionary[GetEntityKey(entity)] = _memoryDbSerializer.Serialize(entity);
+            }
+        }
+
+        public void Remove(TEntity entity)
+        {
+            _dictionary.Remove(GetEntityKey(entity));
+        }
+
+        public bool Contains(TEntity entity)
+        {
+            return _dictionary.ContainsKey(GetEntityKey(entity));
+        }
+
+        private string GetEntityKey(TEntity entity)
+        {
+            return entity.GetKeys().JoinAsString(",");
+        }
+    }
+}
\ No newline at end of file
diff --git a/framework/src/Volo.Abp.MemoryDb/Volo/Abp/Domain/Repositories/MemoryDb/MemoryDbBinarySerializer.cs b/framework/src/Volo.Abp.MemoryDb/Volo/Abp/Domain/Repositories/MemoryDb/MemoryDbBinarySerializer.cs
new file mode 100644
index 0000000000..0dc0fb3e53
--- /dev/null
+++ b/framework/src/Volo.Abp.MemoryDb/Volo/Abp/Domain/Repositories/MemoryDb/MemoryDbBinarySerializer.cs
@@ -0,0 +1,29 @@
+using System.IO;
+using System.Runtime.Serialization.Formatters.Binary;
+using Volo.Abp.DependencyInjection;
+
+namespace Volo.Abp.Domain.Repositories.MemoryDb
+{
+    public class MemoryDbBinarySerializer : IMemoryDbSerializer, ITransientDependency
+    {
+        public object Serialize(object obj)
+        {
+            var stream = new MemoryStream();
+            var formatter = new BinaryFormatter();
+            formatter.Serialize(stream, obj);
+            return stream;
+        }
+
+        public object Deserialize(object obj)
+        {
+            if (!(obj is MemoryStream stream))
+            {
+                return null;
+            }
+
+            var formatter = new BinaryFormatter();
+            stream.Seek(0, SeekOrigin.Begin);
+            return formatter.Deserialize(stream);
+        }
+    }
+}
\ No newline at end of file
diff --git a/framework/src/Volo.Abp.MemoryDb/Volo/Abp/Domain/Repositories/MemoryDb/MemoryDbRepository.cs b/framework/src/Volo.Abp.MemoryDb/Volo/Abp/Domain/Repositories/MemoryDb/MemoryDbRepository.cs
index c658a34ef4..0f82aa798b 100644
--- a/framework/src/Volo.Abp.MemoryDb/Volo/Abp/Domain/Repositories/MemoryDb/MemoryDbRepository.cs
+++ b/framework/src/Volo.Abp.MemoryDb/Volo/Abp/Domain/Repositories/MemoryDb/MemoryDbRepository.cs
@@ -14,7 +14,7 @@ namespace Volo.Abp.Domain.Repositories.MemoryDb
     {
         //TODO: Add dbcontext just like mongodb implementation!
 
-        public virtual List<TEntity> Collection => Database.Collection<TEntity>();
+        public virtual IMemoryDatabaseCollection<TEntity> Collection => Database.Collection<TEntity>();
 
         public virtual IMemoryDatabase Database => DatabaseProvider.GetDatabase();
 
@@ -33,6 +33,7 @@ namespace Volo.Abp.Domain.Repositories.MemoryDb
 
         public override TEntity Update(TEntity entity, bool autoSave = false)
         {
+            Collection.Update(entity);
             return entity;
         }
 
@@ -48,7 +49,7 @@ namespace Volo.Abp.Domain.Repositories.MemoryDb
 
         public override long GetCount()
         {
-            return Collection.Count;
+            return Collection.Count();
         }
 
         protected override IQueryable<TEntity> GetQueryable()
diff --git a/framework/src/Volo.Abp.MemoryDb/Volo/Abp/Domain/Repositories/MemoryDbCoreRepositoryExtensions.cs b/framework/src/Volo.Abp.MemoryDb/Volo/Abp/Domain/Repositories/MemoryDbCoreRepositoryExtensions.cs
index 6f940ca146..1547a581e5 100644
--- a/framework/src/Volo.Abp.MemoryDb/Volo/Abp/Domain/Repositories/MemoryDbCoreRepositoryExtensions.cs
+++ b/framework/src/Volo.Abp.MemoryDb/Volo/Abp/Domain/Repositories/MemoryDbCoreRepositoryExtensions.cs
@@ -13,7 +13,7 @@ namespace Volo.Abp.Domain.Repositories
             return repository.ToMemoryDbRepository().Database;
         }
 
-        public static List<TEntity> GetCollection<TEntity, TKey>(this IBasicRepository<TEntity, TKey> repository)
+        public static IMemoryDatabaseCollection<TEntity> GetCollection<TEntity, TKey>(this IBasicRepository<TEntity, TKey> repository)
             where TEntity : class, IEntity<TKey>
         {
             return repository.ToMemoryDbRepository().Collection;
diff --git a/framework/test/Volo.Abp.TestApp/Volo/Abp/TestApp/Application/PeopleAppService.cs b/framework/test/Volo.Abp.TestApp/Volo/Abp/TestApp/Application/PeopleAppService.cs
index 05c6afb7dc..ef76becbc5 100644
--- a/framework/test/Volo.Abp.TestApp/Volo/Abp/TestApp/Application/PeopleAppService.cs
+++ b/framework/test/Volo.Abp.TestApp/Volo/Abp/TestApp/Application/PeopleAppService.cs
@@ -35,7 +35,7 @@ namespace Volo.Abp.TestApp.Application
             var phone = new Phone(person.Id, phoneDto.Number, phoneDto.Type);
 
             person.Phones.Add(phone);
-
+            Repository.Update(person);
             return ObjectMapper.Map<Phone, PhoneDto>(phone);
         }
 
@@ -43,6 +43,7 @@ namespace Volo.Abp.TestApp.Application
         {
             var person = await GetEntityByIdAsync(id);
             person.Phones.RemoveAll(p => p.Number == number);
+            Repository.Update(person);
         }
 
         public Task<GetWithComplexTypeInput> GetWithComplexType(GetWithComplexTypeInput input)
diff --git a/framework/test/Volo.Abp.TestApp/Volo/Abp/TestApp/Domain/City.cs b/framework/test/Volo.Abp.TestApp/Volo/Abp/TestApp/Domain/City.cs
index 76361463d7..92df3a166e 100644
--- a/framework/test/Volo.Abp.TestApp/Volo/Abp/TestApp/Domain/City.cs
+++ b/framework/test/Volo.Abp.TestApp/Volo/Abp/TestApp/Domain/City.cs
@@ -3,6 +3,7 @@ using Volo.Abp.Domain.Entities;
 
 namespace Volo.Abp.TestApp.Domain
 {
+    [Serializable]
     public class City : AggregateRoot<Guid>
     {
         public string Name { get; set; }
diff --git a/framework/test/Volo.Abp.TestApp/Volo/Abp/TestApp/Domain/Person.cs b/framework/test/Volo.Abp.TestApp/Volo/Abp/TestApp/Domain/Person.cs
index 8235225def..9b017ef51f 100644
--- a/framework/test/Volo.Abp.TestApp/Volo/Abp/TestApp/Domain/Person.cs
+++ b/framework/test/Volo.Abp.TestApp/Volo/Abp/TestApp/Domain/Person.cs
@@ -7,6 +7,7 @@ using Volo.Abp.MultiTenancy;
 namespace Volo.Abp.TestApp.Domain
 {
     [AutoMapTo(typeof(PersonEto))]
+    [Serializable]
     public class Person : FullAuditedAggregateRoot<Guid>, IMultiTenant
     {
         public virtual Guid? TenantId { get; set; }
diff --git a/framework/test/Volo.Abp.TestApp/Volo/Abp/TestApp/Domain/Phone.cs b/framework/test/Volo.Abp.TestApp/Volo/Abp/TestApp/Domain/Phone.cs
index e53f2bc2e3..43087a7d87 100644
--- a/framework/test/Volo.Abp.TestApp/Volo/Abp/TestApp/Domain/Phone.cs
+++ b/framework/test/Volo.Abp.TestApp/Volo/Abp/TestApp/Domain/Phone.cs
@@ -7,6 +7,7 @@ using Volo.Abp.Domain.Entities;
 namespace Volo.Abp.TestApp.Domain
 {
     [Table("AppPhones")]
+    [Serializable]
     public class Phone : Entity
     {
         public virtual Guid PersonId { get; set; }