Abstract: In this paper, the multiyear mean features and their seasonal, monthly, yearly and interdecadal changes for the air column precipitable water ( hereafter PW ) over the Launch Site and its surroundings have been analyzed, utilizing the NCEP's monthly mean precipitable water reanalyzed gridded data and the observed rainfall data from 1974 to 2010. The results show that there exist the obviously seasonal, monthly, yearly and interdecadal changes of the PW over the Launch Site. It shows wetter in the south than that in the north at all seasons. There are maximum PW in summer and the minimum PW in winter. The air column PW over Launch Site presents approximately a southeast - northwestern U - shaped pattern. The monthly variations of PW show the "corridor - barrier" effect of Launch Site. The summer averaged PW displays a marked difference between the wet and dry years. Furthermore, there are apparent differences in the PW conversion rate into precipitation in various parts of the Launch Site and its surroundings. Above all have influenced the precipitation climate change of the Launch Site