diff --git a/csst_mci_sim/support/shao.py b/csst_mci_sim/support/shao.py
index 2cb5006342edac0713d17e2e22a8dc61ca795058..50d73b296bdebeb50d52156f09be4b87bd858f6f 100644
--- a/csst_mci_sim/support/shao.py
+++ b/csst_mci_sim/support/shao.py
@@ -50,7 +50,7 @@ def onOrbitObsPosition(path, input_ra_list, input_dec_list, input_pmra_list, inp
     input_vy = input_vy*1000.0
     input_vz = input_vz*1000.0
 
-    if  isinstance(type(input_date_str), type("2025-03-05")):
+    if isinstance(type(input_date_str), type("2025-03-05")):
         # type(input_date_str) != type("2025-03-05"):
         raise TypeError("Parameter 15 is not string!", input_date_str)
     else: