diff --git a/deep_inject_test.go b/deep_inject_test.go
new file mode 100644
index 0000000..7b38060
--- /dev/null
+++ b/deep_inject_test.go
@@ -0,0 +1,149 @@
+package inject
+
+import "testing"
+
+// 测试深度注入的各种场景
+func TestDeepInjectAdvanced(t *testing.T) {
+	// 场景1: 多层嵌套的手动注入实例
+	type Level3 struct {
+		Value string
+	}
+
+	type Level2 struct {
+		L3 *Level3 `inject:""`
+	}
+
+	type Level1 struct {
+		L2 *Level2 `inject:""`
+	}
+
+	type Root struct {
+		L1 *Level1 `inject:""`
+	}
+
+	var g Graph
+
+	// 手动创建嵌套结构
+	root := &Root{
+		L1: &Level1{
+			L2: &Level2{
+				L3: &Level3{Value: "manually created"},
+			},
+		},
+	}
+
+	// 提供根对象
+	if err := g.Provide(&Object{Value: root}); err != nil {
+		t.Fatal("failed to provide root:", err)
+	}
+
+	// 执行深度注入
+	if err := g.Populate(); err != nil {
+		t.Fatal("failed to populate:", err)
+	}
+
+	// 验证深度注入是否成功
+	if root.L1 == nil {
+		t.Fatal("root.L1 should not be nil")
+	}
+	if root.L1.L2 == nil {
+		t.Fatal("root.L1.L2 should not be nil")
+	}
+	if root.L1.L2.L3 == nil {
+		t.Fatal("root.L1.L2.L3 should not be nil")
+	}
+	if root.L1.L2.L3.Value != "manually created" {
+		t.Fatal("deep injected value should be preserved")
+	}
+}
+
+func TestDeepInjectWithMixedProvision(t *testing.T) {
+	// 场景2: 混合手动创建和依赖注入提供的实例
+	type ServiceA struct {
+		Name string
+	}
+
+	type ServiceB struct {
+		A *ServiceA `inject:""`
+	}
+
+	type ServiceC struct {
+		B *ServiceB `inject:""`
+	}
+
+	var g Graph
+
+	// 手动提供ServiceA
+	serviceA := &ServiceA{Name: "ServiceA"}
+	if err := g.Provide(&Object{Value: serviceA}); err != nil {
+		t.Fatal("failed to provide serviceA:", err)
+	}
+
+	// 手动创建包含部分依赖的ServiceC
+	serviceC := &ServiceC{
+		B: &ServiceB{}, // B没有A的依赖
+	}
+
+	if err := g.Provide(&Object{Value: serviceC}); err != nil {
+		t.Fatal("failed to provide serviceC:", err)
+	}
+
+	// 执行注入
+	if err := g.Populate(); err != nil {
+		t.Fatal("failed to populate:", err)
+	}
+
+	// 验证混合注入结果
+	if serviceC.B == nil {
+		t.Fatal("serviceC.B should not be nil")
+	}
+	if serviceC.B.A == nil {
+		t.Fatal("serviceC.B.A should be injected")
+	}
+	if serviceC.B.A != serviceA {
+		t.Fatal("serviceC.B.A should be the same instance as serviceA")
+	}
+	if serviceC.B.A.Name != "ServiceA" {
+		t.Fatal("injected service should preserve its properties")
+	}
+}
+
+func TestDeepInjectCircularDependency(t *testing.T) {
+	// 场景3: 测试循环依赖的处理（这应该能正常工作）
+	type CircularB struct {
+		A interface{} `inject:""`
+	}
+
+	type CircularA struct {
+		B *CircularB `inject:""`
+	}
+
+	var g Graph
+
+	// 手动创建一个带有循环依赖的结构
+	a := &CircularA{}
+	b := &CircularB{A: a}
+	a.B = b
+
+	// 提供到依赖图
+	if err := g.Provide(&Object{Value: a}); err != nil {
+		t.Fatal("failed to provide a:", err)
+	}
+
+	if err := g.Provide(&Object{Value: b}); err != nil {
+		t.Fatal("failed to provide b:", err)
+	}
+
+	// 执行注入
+	if err := g.Populate(); err != nil {
+		t.Fatal("failed to populate:", err)
+	}
+
+	// 验证循环依赖保持完整
+	if a.B != b {
+		t.Fatal("circular dependency should be preserved")
+	}
+	if b.A.(*CircularA) != a {
+		t.Fatal("circular dependency should be preserved")
+	}
+}
diff --git a/inject.go b/inject.go
index 215f8b6..e46db4f 100644
--- a/inject.go
+++ b/inject.go
@@ -114,6 +114,56 @@ func (g *Graph) Provide(objects ...*Object) error {
 	return nil
 }
 
+// provideForDeepInject 专门用于深度注入时提供对象，允许同类型的多个实例
+func (g *Graph) provideForDeepInject(o *Object) error {
+	o.reflectType = reflect.TypeOf(o.Value)
+	o.reflectValue = reflect.ValueOf(o.Value)
+
+	if o.Fields != nil {
+		return fmt.Errorf("fields were specified on object %v when it was provided", o)
+	}
+
+	if o.Name == "" {
+		if !isStructPtr(o.reflectType) {
+			return fmt.Errorf(
+				"expected unnamed object value to be a pointer to a struct but got type %s with value %v",
+				o.reflectType,
+				o.Value)
+		}
+
+		// 对于深度注入，我们不检查类型重复，直接添加到unnamed列表
+		// 但我们需要检查是否已经存在相同的实例（相同的指针）
+		for _, existing := range g.unnamed {
+			if existing.Value == o.Value {
+				// 相同的实例已存在，不需要重复添加
+				return nil
+			}
+		}
+
+		g.unnamed = append(g.unnamed, o)
+	} else {
+		if g.named == nil {
+			g.named = make(map[string]*Object)
+		}
+
+		if g.named[o.Name] != nil {
+			return fmt.Errorf("provided two instances named %s", o.Name)
+		}
+		g.named[o.Name] = o
+	}
+
+	if g.Logger != nil {
+		if o.created {
+			g.Logger.Info("created %v", o)
+		} else if o.embedded {
+			g.Logger.Info("provided embedded %v", o)
+		} else {
+			g.Logger.Info("provided %v for deep injection", o)
+		}
+	}
+	return nil
+}
+
 // Populate 填充不完整的对象
 func (g *Graph) Populate() error {
 	for _, o := range g.named {
@@ -235,14 +285,16 @@ StructLoop:
 						private: false,
 						created: false,
 					}
-					if err := g.Provide(existingObject); err == nil {
-						// 递归填充现有对象的依赖（深度注入）
-						if err := g.populateExplicit(existingObject); err != nil {
-							return err
-						}
-						if g.Logger != nil {
-							g.Logger.Info("deep injected existing %v in field %s of %v", existingObject, o.reflectType.Elem().Field(i).Name, o)
-						}
+					// 对于深度注入，我们需要特殊处理类型重复的情况
+					if err := g.provideForDeepInject(existingObject); err != nil {
+						return fmt.Errorf("failed to provide existing object for deep injection: %v", err)
+					}
+					// 递归填充现有对象的依赖（深度注入）
+					if err := g.populateExplicit(existingObject); err != nil {
+						return err
+					}
+					if g.Logger != nil {
+						g.Logger.Info("deep injected existing %v in field %s of %v", existingObject, o.reflectType.Elem().Field(i).Name, o)
 					}
 				}
 			}
diff --git a/inject_test.go b/inject_test.go
index 0976fbc..d2e422c 100644
--- a/inject_test.go
+++ b/inject_test.go
@@ -998,6 +998,7 @@ type TypeAForTestDeepInject struct {
 }
 
 type TypeBForTestDeepInject struct {
+	A *TypeAForTestDeepInject `inject:""`
 }
 
 type TypeCForTestDeepInject struct {
@@ -1046,4 +1047,7 @@ func TestForDeepInject(t *testing.T) {
 	if d.A.C.B == nil {
 		t.Fatal("d.A.C.B is nil")
 	}
+	if b.A == nil {
+		t.Fatal("b.A is nil")
+	}
 }