Abstract: This paper comprehensively analyzed a rainstorm process in 2008 using GPS-PWV obtained from the ground-based GPS in Chengdu and drew the conclusion that there was the certain correlation between the change of GPS-PWV and actual precipitation.Results showed that GPS-PWV was highly sensitive to the change of water vapor in the air,which could reflect its time-space change timely.The maximum of precipitation intensity lagged behind the peak of precipitable water vapor and was a bit ahead of the precipitation.The strong ascending movement contributed to the cumulative increase of PWV and its intensity was significantly correlated to the magnitude of GPS-PWV.When GPS-PWV was in the high value area,the atmosphere was always at the unstable status.