diff --git a/Storage/Storage.Test/ObjectTest.cs b/Storage/Storage.Test/ObjectTest.cs
index 399f2af..1d0f92b 100644
--- a/Storage/Storage.Test/ObjectTest.cs
+++ b/Storage/Storage.Test/ObjectTest.cs
@@ -5,6 +5,8 @@ using System.Collections.Generic;
 using LeanCloud;
 using LeanCloud.Storage;
 
+using static NUnit.Framework.TestContext;
+
 namespace Storage.Test {
     public class ObjectTest {
         [SetUp]
@@ -144,5 +146,25 @@ namespace Storage.Test {
             TestContext.WriteLine(hello["content"]);
             Assert.IsNull(hello["content"]);
         }
+
+        [Test]
+        public async Task OperateNullProperty() {
+            LCObject obj = new LCObject("Hello");
+            obj.Increment("intValue", 123);
+            obj.Increment("intValue", 321);
+            obj.Add("intList", 1);
+            obj.Add("intList", 2);
+            obj.Add("intList", 3);
+            await obj.Save();
+
+            WriteLine(obj["intValue"]);
+            Assert.AreEqual(obj["intValue"], 444);
+            List<object> intList = obj["intList"] as List<object>;
+            WriteLine(intList.Count);
+            Assert.AreEqual(intList.Count, 3);
+            Assert.AreEqual(intList[0], 1);
+            Assert.AreEqual(intList[1], 2);
+            Assert.AreEqual(intList[2], 3);
+        }
     }
 }
diff --git a/Storage/Storage/Internal/Operation/LCAddOperation.cs b/Storage/Storage/Internal/Operation/LCAddOperation.cs
index 0d1ae4d..9591e65 100644
--- a/Storage/Storage/Internal/Operation/LCAddOperation.cs
+++ b/Storage/Storage/Internal/Operation/LCAddOperation.cs
@@ -1,6 +1,7 @@
 using System;
 using System.Collections;
 using System.Collections.Generic;
+using System.Linq;
 using LeanCloud.Storage.Internal.Codec;
 
 namespace LeanCloud.Storage.Internal.Operation {
@@ -16,11 +17,15 @@ namespace LeanCloud.Storage.Internal.Operation {
                 return previousOp;
             }
             if (previousOp is LCAddOperation addOp) {
-                valueList.AddRange(addOp.valueList);
+                List<object> list = new List<object>(addOp.valueList);
+                list.AddRange(valueList);
+                valueList = list;
                 return this;
             }
             if (previousOp is LCAddUniqueOperation addUniqueOp) {
-                valueList.AddRange(addUniqueOp.values);
+                List<object> list = addUniqueOp.values.ToList();
+                list.AddRange(valueList);
+                valueList = list;
                 return this;
             }
             throw new ArgumentException("Operation is invalid after previous operation.");
diff --git a/Storage/Storage/Internal/Operation/LCRemoveOperation.cs b/Storage/Storage/Internal/Operation/LCRemoveOperation.cs
index 4a2f57a..bf75437 100644
--- a/Storage/Storage/Internal/Operation/LCRemoveOperation.cs
+++ b/Storage/Storage/Internal/Operation/LCRemoveOperation.cs
@@ -17,7 +17,10 @@ namespace LeanCloud.Storage.Internal.Operation {
                 return previousOp;
             }
             if (previousOp is LCRemoveOperation removeOp) {
-                valueList.AddRange(removeOp.valueList);
+                List<object> list = new List<object>(removeOp.valueList);
+                list.AddRange(valueList);
+                valueList = list;
+                return this;
             }
             throw new ArgumentException("Operation is invalid after previous operation.");
         }
@@ -30,7 +33,10 @@ namespace LeanCloud.Storage.Internal.Operation {
         }
 
         public object Apply(object oldValue, string key) {
-            List<object> list = new List<object>(oldValue as IEnumerable<object>);
+            List<object> list = new List<object>();
+            if (oldValue != null) {
+                list.AddRange(oldValue as IEnumerable<object>);
+            }
             list.RemoveAll(item => valueList.Contains(item));
             return list;
         }
diff --git a/Storage/Storage/LCObject.cs b/Storage/Storage/LCObject.cs
index c61cd33..b99e7d6 100644
--- a/Storage/Storage/LCObject.cs
+++ b/Storage/Storage/LCObject.cs
@@ -420,11 +420,6 @@ namespace LeanCloud.Storage {
         }
 
         void ApplyOperation(string key, ILCOperation op) {
-            if (operationDict.TryGetValue(key, out ILCOperation previousOp)) {
-                operationDict[key] = op.MergeWithPrevious(previousOp);
-            } else {
-                operationDict[key] = op;
-            }
             if (op is LCDeleteOperation) {
                 estimatedData.Remove(key);
             } else {
@@ -434,6 +429,11 @@ namespace LeanCloud.Storage {
                     estimatedData[key] = op.Apply(null, key);
                 }
             }
+            if (operationDict.TryGetValue(key, out ILCOperation previousOp)) {
+                operationDict[key] = op.MergeWithPrevious(previousOp);
+            } else {
+                operationDict[key] = op;
+            }
         }
 
         internal void Merge(LCObjectData objectData) {