diff --git a/tests/test_astrometry.py b/tests/test_astrometry.py
new file mode 100644
index 0000000000000000000000000000000000000000..8947ce3dc408835be54090da0632683debb0379a
--- /dev/null
+++ b/tests/test_astrometry.py
@@ -0,0 +1,56 @@
+import unittest
+import os
+import sys
+from astropy.time import Time
+from datetime import datetime
+
+from ObservationSim.Astrometry.Astrometry_util import on_orbit_obs_position
+
+
+class TestAstrometry(unittest.TestCase):
+    def __init__(self, methodName='runTest'):
+        super(TestAstrometry, self).__init__(methodName)
+        # self.dataPath = os.path.join(
+        #     os.getenv('UNIT_TEST_DATA_ROOT'), 'csst_msc_sim/csst_fz_msc')
+
+    def test_astrometry_method(self):
+        ra_list = [300.061827]
+        dec_list = [-60.132741]
+        pmra_list = [0.]
+        pmdec_list = [0.]
+        rv_list = [0.]
+        parallax_list = [1e-9]
+        sat_x = 5227.7501
+        sat_y = -1521.2218
+        sat_z = -4007.7662
+        sat_vx = 0.13581745522969868
+        sat_vy = 7.233066646238058
+        sat_vz = -2.5770060087052116
+        dt = datetime.utcfromtimestamp(Time(jdt, format='jd').unix)
+        date_str = dt.date().isoformat()
+        time_str = dt.time().isoformat()
+        ra_arr, dec_arr = on_orbit_obs_position(
+            input_ra_list=ra_list,
+            input_dec_list=dec_list,
+            input_pmra_list=pmra_list,
+            input_pmdec_list=pmdec_list,
+            input_rv_list=rv_list,
+            input_parallax_list=parallax_list,
+            input_nstars=len(ra_list),
+            input_x=sat_x,
+            input_y=sat_y,
+            input_z=sat_z,
+            input_vx=sat_vx,
+            input_vy=sat_vy,
+            input_vz=sat_vz,
+            input_epoch="J2000",
+            input_date_str=date_str,
+            input_time_str=time_str
+        )
+        print(ra_arr[0], dec_arr[0])
+        self.assertTrue(ra_arr[0] != ra_list[0])
+        self.assertTrue(dec_arr[0] != dec_list[0])
+
+
+if __name__ == '__main_':
+    unittest.main()