diff --git a/csst_dfs_api/facility/calmerge.py b/csst_dfs_api/facility/calmerge.py
index c98595a79b057bfd0b7d3ed84fffa7f85df57f21..26694408b9b82b3bf54cbce739b3f248af313681 100644
--- a/csst_dfs_api/facility/calmerge.py
+++ b/csst_dfs_api/facility/calmerge.py
@@ -24,6 +24,17 @@ class CalMergeApi(object):
         :returns: csst_dfs_common.models.Result
         '''
         return self.stub.find(**kwargs)
+    
+    def get_latest_by_l0(self, **kwargs):
+        ''' retrieve calibration merge records from database by level0 data
+        
+        :param kwargs: Parameter dictionary, key items support:
+            level0_id: [str],
+            ref_type: [str]
+
+        :returns: csst_dfs_common.models.Result
+        '''
+        return self.stub.get_latest_by_l0(**kwargs)
 
     def get(self, **kwargs):
         '''  fetch a record from database
diff --git a/tests/test_facility_cal_merge.py b/tests/test_facility_cal_merge.py
index d11d92e76083af9bc6944962080ffcbed5c3d206..3fb5e74e2d2e4316daa5955fa4674ebc014f7b6b 100644
--- a/tests/test_facility_cal_merge.py
+++ b/tests/test_facility_cal_merge.py
@@ -15,6 +15,10 @@ class CalMergeApiTestCase(unittest.TestCase):
             obs_time = ("2021-06-01 11:12:13","2021-06-08 11:12:13"))
         print('find:', recs)
 
+    def test_get_latest_by_l0(self):
+        rec = self.api.get_latest_by_l0(level0_id='000001102', ref_type = "bias")
+        print('get_latest_by_l0:', rec)
+
     def test_get(self):
         rec = self.api.get(id = 3)
         print('get by id:', rec)
diff --git a/tests/test_facility_level0.py b/tests/test_facility_level0.py
index 6ef8d2202af3508de2feed918b85259b5c9e51f7..b03ff07025b04c1bde07ab24a20c7a3ea1bcb619 100644
--- a/tests/test_facility_level0.py
+++ b/tests/test_facility_level0.py
@@ -30,9 +30,9 @@ class Level0DataTestCase(unittest.TestCase):
 
     def test_write(self):
         rec = self.api.write(
-            level0_id = '000001102',
+            level0_id = '000001101',
             obs_id = '0000011',
-            detector_no = "02",
+            detector_no = "01",
             obs_type = "sci",            
             obs_time = "2021-06-06 11:12:13",
             exp_time = 150,