Abstract:COSMIC-2 provides continuous atmospheric data for improving weather forecasts, which are helpful for monitoring and warning of extreme weather. We divide Chinese mainland into five regions according to climate type and analyze the accuracy of COSMIC-2 PWV in Chinese mainland based on the water vapor sequence of CMONOC station. From the perspectives of distance and elevation between stations, we design the PWV matching scheme of COSMIC-2 occultation points and GNSS stations. We evaluate the accuracy of COSMIC-2 for different climate types in China. The results show that the RMSE of plateau mountain, temperate continental, temperate monsoon, subtropical monsoon, and tropical monsoon climate types are 1.40 mm, 1.49 mm, 2.68 mm, 3.11 mm, and 3.16 mm, respectively. The accuracy in inland area is better than that in coastal area.