Abstract: The characteristics analysis of precipitable water vapor (PWV) change before and after earthquakes can provide reference for earthquake prediction and early warning of secondary disasters after earthquakes. In this paper, the abnormal changes of GNSS ZTD (PWV) before and after earthquakes are studied with the method of wavelet transform. By combining ZTD, seismic and precipitation data, the characteristics of water vapor change before and after earthquakes are analyzed. The ZTD data is decomposed and reconstructed by wavelet transform, and the abnormal changes of GNSS ZTD before and after earthquakes is analyzed. It is found that there is a sudden change of water vapor before and after earthquakes, and the ZTD after wavelet transform can clearly show the relationship between the characteristics of water vapor change and earthquakes and the change of water vapor cycle after earthquakes.