diff --git a/collection.go b/collection.go
index 6975e92..ab6e9df 100644
--- a/collection.go
+++ b/collection.go
@@ -21,6 +21,19 @@ func (receiver *Collection[T]) Add(item ...T) {
 	}
 }
 
+// AddIfNotExists 如果元素不存在，则添加元素
+func (receiver *Collection[T]) AddIfNotExists(item T) {
+	receiver.lock.Lock()
+	defer receiver.lock.Unlock()
+
+	for _, t := range *receiver.source {
+		if parse.IsEqual(t, item) {
+			return
+		}
+	}
+	*receiver.source = append(*receiver.source, item)
+}
+
 // AddRange 添加元素
 func (receiver *Collection[T]) AddRange(lst Enumerable[T]) {
 	if lst.Count() > 0 {
diff --git a/test/collection_test.go b/test/collection_test.go
index 28802d5..32aedcd 100644
--- a/test/collection_test.go
+++ b/test/collection_test.go
@@ -23,6 +23,15 @@ func Test_collection_Add(t *testing.T) {
 	assert.Equal(t, 3, lst.Index(2))
 }
 
+func Test_collection_AddIfNotExists(t *testing.T) {
+	lst := collections.NewList[int](1, 2)
+	lst.AddIfNotExists(1)
+	lst.AddIfNotExists(2)
+	lst.AddIfNotExists(3)
+	assert.Equal(t, 3, lst.Count())
+	assert.Equal(t, 3, lst.Index(2))
+}
+
 func Test_collection_AddRange(t *testing.T) {
 	lst := collections.NewList[int]()
 	lst2 := collections.NewList[int](1, 2, 3)