The key parameters including air pressure,air temperature,water vapor weighted mean temperature (T_m) and Zenith Total Delay (ZTD),which are involved in GNSS precipitable water vapor retrieval,are estimated based on CRA40 released by China Meteorological Administration.The accuracy and reliability of the estimated key parameters over China are comprehensively evaluated,taking data of ground meteorological station,radiosonde station and GNSS station as reference.The performance of CRA40 is compared with the latest ECMWF global reanalysis,ERA5.The results illustrate that CRA40 performs slightly worse than ERA5 in aspects of air pressure and ZTD,with average Root Mean Squares (RMS) of 0.91 hPa and 13.5 mm,respectively.While CRA40 is generally superior to ERA5 in air temperature and T_m estimation,with RMS of 2.67 K and 1.47 K,respectively.The diurnal variations of three parameters including air pressure,air temperature and ZTD estimated from CRA40 generally agree well with the in-situ measurements.