diff --git a/Utilities/DataHelper/include/DataHelper/TrackerHitHelper.h b/Utilities/DataHelper/include/DataHelper/TrackerHitHelper.h
index fcd9dd146b9268b581eb2246f89b1615fc3fb6db..319bbebf6491c5c70b4c6f933749dce8bcd594f9 100644
--- a/Utilities/DataHelper/include/DataHelper/TrackerHitHelper.h
+++ b/Utilities/DataHelper/include/DataHelper/TrackerHitHelper.h
@@ -2,13 +2,29 @@
 #define TrackerHitHelper_H
 
 #include "edm4hep/TrackerHit.h"
+#include "edm4hep/SimTrackerHit.h"
+#include "edm4hep/MCRecoTrackerAssociationCollection.h"
+#include "DDSegmentation/Segmentation.h"
+#include "DetSegmentation/GridDriftChamber.h"
 #include <array>
 
+//namespace dd4hep {
+//         class Detector;
+//         namespace DDSegmentation{
+//             class GridDriftChamber;
+//         }
+//}
+
 namespace CEPC{
   std::array<float, 6> GetCovMatrix(edm4hep::TrackerHit& hit, bool useSpacePointerBuilderMethod = false);
   float                GetResolutionRPhi(edm4hep::TrackerHit& hit);
   float                GetResolutionZ(edm4hep::TrackerHit& hit);
   std::array<float, 6> ConvertToCovXYZ(float dU, float thetaU, float phiU, float dV, float thetaV, float phiV, bool useSpacePointBuilderMethod = false);
+  const edm4hep::SimTrackerHit getAssoClosestSimTrackerHit(
+          const edm4hep::MCRecoTrackerAssociationCollection* assoHits,
+          const edm4hep::TrackerHit trackerHit,
+          const dd4hep::DDSegmentation::GridDriftChamber* segmentation,
+          int docaMehtod);
 }
 
 #endif