Abstract：Based on precise point positioning(PPP),we use RTKLib, CSRS, MagicGNSS and CGline to calculate the accuracy of zenith tropospheric delay(ZTD) under different spatiotemporal conditions. The results show that: 1) The ZTD accuracy of four PPP softwares are CSRS-PPP, MagicGNSS, RTKLib and CGline from highest to lowest. 2) Under different geographical locations, the ZTD accuracy of four PPP softwares from high to low is northern hemisphere, southern hemisphere and equator. 3) The RTKlib-ZTD is greatly affected by seasons, and the RMSE are summer, spring, autumn and winter from highest to lowest, while different seasons have little influence on the ZTD of other online solution systems. In general, the average ZTD RMSE of four PPP softwares are better than 1 cm, which meets the current application of real-time and post-processing GNSS meteorology.