diff --git a/internal/service/cloud115/cloud115_test.go b/internal/service/cloud115/cloud115_test.go
index d1c704d..aaf5dfd 100644
--- a/internal/service/cloud115/cloud115_test.go
+++ b/internal/service/cloud115/cloud115_test.go
@@ -371,7 +371,62 @@ func TestThrottleCodeHandling(t *testing.T) {
 	if err == nil {
 		t.Fatal("expected throttle error")
 	}
-	if !tm.IsThrottled() {
-		t.Fatal("code 770004 should trigger throttle status")
+		if !tm.IsThrottled() {
+			t.Fatal("code 770004 should trigger throttle status")
+		}
 	}
-}
+
+	func TestRemoteFileDetailRelativePath(t *testing.T) {
+		rootCID := "3238787832374488117" // 影视库
+
+		// 场景 1：115 目录 paths 中只有祖先目录链，不包含自身
+		d1 := &RemoteFileDetail{
+			FileId:   "3251154147730910635",
+			FileName: "出包王女",
+			Paths: []struct {
+				FileId string `json:"file_id"`
+				Name   string `json:"file_name"`
+			}{
+				{FileId: "0", Name: "根目录"},
+				{FileId: "3238787832374488117", Name: "影视库"},
+				{FileId: "3238787913223892116", Name: "动漫"},
+			},
+		}
+		if got := d1.RelativePath(rootCID); got != "动漫/出包王女" {
+			t.Errorf("d1.RelativePath = %q, want %q", got, "动漫/出包王女")
+		}
+
+		// 场景 2：祖先中间目录，自身在 paths 末尾
+		d2 := &RemoteFileDetail{
+			FileId:   "3238787913223892116",
+			FileName: "动漫",
+			Paths: []struct {
+				FileId string `json:"file_id"`
+				Name   string `json:"file_name"`
+			}{
+				{FileId: "0", Name: "根目录"},
+				{FileId: "3238787832374488117", Name: "影视库"},
+				{FileId: "3238787913223892116", Name: "动漫"},
+			},
+		}
+		if got := d2.RelativePath(rootCID); got != "动漫" {
+			t.Errorf("d2.RelativePath = %q, want %q", got, "动漫")
+		}
+
+		// 场景 3：根同步目录自身
+		d3 := &RemoteFileDetail{
+			FileId:   rootCID,
+			FileName: "影视库",
+			Paths: []struct {
+				FileId string `json:"file_id"`
+				Name   string `json:"file_name"`
+			}{
+				{FileId: "0", Name: "根目录"},
+				{FileId: rootCID, Name: "影视库"},
+			},
+		}
+		if got := d3.RelativePath(rootCID); got != "" {
+			t.Errorf("d3.RelativePath = %q, want %q", got, "")
+		}
+	}
+
diff --git a/internal/service/cloud115/open.go b/internal/service/cloud115/open.go
index bbbd0b9..44c64c6 100644
--- a/internal/service/cloud115/open.go
+++ b/internal/service/cloud115/open.go
@@ -145,12 +145,15 @@ type RemoteFileDetail struct {
 
 // RelativePath 计算该目录相对于根同步目录（rootCID）的相对路径。
 func (d *RemoteFileDetail) RelativePath(rootCID string) string {
-	if d == nil || len(d.Paths) == 0 {
+	if d == nil {
 		return ""
 	}
 	if rootCID == "" {
 		rootCID = "0"
 	}
+	if d.FileId == rootCID {
+		return ""
+	}
 	rootIdx := -1
 	for i, p := range d.Paths {
 		if p.FileId == rootCID {
@@ -165,12 +168,20 @@ func (d *RemoteFileDetail) RelativePath(rootCID string) string {
 	} else if len(d.Paths) > 0 && (d.Paths[0].FileId == "0" || d.Paths[0].FileId == "") {
 		start = 1
 	}
+	hasSelf := false
 	for i := start; i < len(d.Paths); i++ {
+		if d.Paths[i].FileId == d.FileId {
+			hasSelf = true
+		}
 		name := strings.TrimSpace(d.Paths[i].Name)
 		if name != "" {
 			segments = append(segments, name)
 		}
 	}
+	// 若 115 返回的 paths 祖先链未包含当前目录自身，则将其自身目录名 FileName 补在末尾
+	if !hasSelf && strings.TrimSpace(d.FileName) != "" && d.FileId != rootCID {
+		segments = append(segments, strings.TrimSpace(d.FileName))
+	}
 	return strings.Join(segments, "/")
 }
 
diff --git a/internal/service/strm_sync.go b/internal/service/strm_sync.go
index 4c34ebe..71e00bd 100644
--- a/internal/service/strm_sync.go
+++ b/internal/service/strm_sync.go
@@ -582,10 +582,11 @@ func (st *strmSyncState) walk115Flat(open115 *cloud115.OpenClient) error {
 							continue
 						}
 						if _, loaded := st.dirCache.Load(ancestor.FileId); !loaded {
-							subDetail := &cloud115.RemoteFileDetail{
-								FileId: ancestor.FileId,
-								Paths:  nil,
-							}
+								subDetail := &cloud115.RemoteFileDetail{
+									FileId:   ancestor.FileId,
+									FileName: ancestor.Name,
+									Paths:    nil,
+								}
 							for _, p := range detail.Paths {
 								subDetail.Paths = append(subDetail.Paths, p)
 								if p.FileId == ancestor.FileId {
diff --git a/test_rel.go b/test_rel.go
new file mode 100644
index 0000000..e4e8682
--- /dev/null
+++ b/test_rel.go
@@ -0,0 +1,25 @@
+package main
+import (
+	"context"
+	"fmt"
+	"github.com/ShukeBta/MMTL/internal/service"
+	"github.com/ShukeBta/MMTL/internal/service/cloud115"
+	"go.uber.org/zap"
+)
+func main() {
+	crypto := service.NewCryptoService("test-secret", zap.NewNop())
+	// Let's test with a mock RemoteFileDetail
+	d := &cloud115.RemoteFileDetail{
+		FileId: "3251154147730910635",
+		FileName: "出包王女",
+		Paths: []struct {
+			FileId string 
+			Name   string 
+		}{
+			{FileId: "0", Name: "根目录"},
+			{FileId: "3238787832374488117", Name: "影视库"},
+			{FileId: "3238787913223892116", Name: "动漫"},
+		},
+	}
+	fmt.Println("RelativePath when rootCID is 3238787832374488117:", d.RelativePath("3238787832374488117"))
+}