Calibration measurements of pyranometers at the Shang Dianzi Regional GAW ( Global Atmospheric Watch) Station are presented in this manuscript. The results show that the sensitivity of pyranometer determined by the CM22 is very agreeable to those determined by HF cavity radiometer which is used as a standard for pyranometers. The difference of the sensitivities determined by two standards is no more than ±0.1 μV·W-1·m2, and the difference of their induced solar shortwave irradiances is generally within ±5 W·m-2.In summery, the portable CM22 pyranometer can be used as the reference of pyranometer in GAW field calibration, and their calibration sensitivities satisfy with accuracy requirement of the BSRN (Baseline Surface Radiation Network) operations. 