diff --git a/local-tool/server/internal/flash/service.go b/local-tool/server/internal/flash/service.go
index 80fa41b..676cce2 100644
--- a/local-tool/server/internal/flash/service.go
+++ b/local-tool/server/internal/flash/service.go
@@ -66,13 +66,15 @@ func resolveModelPath(filePath string, deviceType string) string {
 type Service struct {
 	deviceMgr *device.Manager
 	modelRepo *model.Repository
+	dataDir   string
 	tracker   *ProgressTracker
 }
 
-func NewService(deviceMgr *device.Manager, modelRepo *model.Repository) *Service {
+func NewService(deviceMgr *device.Manager, modelRepo *model.Repository, dataDir string) *Service {
 	return &Service{
 		deviceMgr: deviceMgr,
 		modelRepo: modelRepo,
+		dataDir:   dataDir,
 		tracker:   NewProgressTracker(),
 	}
 }
@@ -106,6 +108,18 @@ func (s *Service) StartFlash(deviceID, modelID string) (string, <-chan driver.Fl
 		return "", nil, fmt.Errorf("model %s has no .nef file path", modelID)
 	}
 
+	// models.json 的 filePath 是相對路徑（例如 "data/nef/kl520/xxx.nef"）。
+	// 如果不是絕對路徑，用 dataDir 解析：
+	//   "data/nef/..." → 去掉 "data/" 前綴 → dataDir + "/nef/..."
+	//   其他相對路徑 → dataDir + "/" + filePath
+	if !filepath.IsAbs(modelPath) {
+		if strings.HasPrefix(modelPath, "data/") || strings.HasPrefix(modelPath, "data\\") {
+			modelPath = filepath.Join(s.dataDir, modelPath[len("data/"):])
+		} else {
+			modelPath = filepath.Join(s.dataDir, modelPath)
+		}
+	}
+
 	modelPath = resolveModelPath(modelPath, deviceInfo.Type)
 
 	taskID := fmt.Sprintf("flash-%s-%s", deviceID, modelID)
diff --git a/local-tool/server/main.go b/local-tool/server/main.go
index 87fd4c9..3c77b2c 100644
--- a/local-tool/server/main.go
+++ b/local-tool/server/main.go
@@ -139,7 +139,7 @@ func main() {
 	cameraMgr := camera.NewManager(cfg.MockCamera)
 
 	// Initialize services
-	flashSvc := flash.NewService(deviceMgr, modelRepo)
+	flashSvc := flash.NewService(deviceMgr, modelRepo, dataDir)
 	inferenceSvc := inference.NewService(deviceMgr)
 
 	// Determine static file system for embedded frontend