Abstract: With the analysis of 132 cases of the Southwest China vortex from May to October 2007-2010,it summarized the form reason,movement and the precipitation features of the Southwest vortex which impacted Xichang launch site,it also induced the characteristics of the Southwest vortex according to wind field,humidity field,temperature field and other aspects,the article proposed the key to forecast various types of Southwest vortex,built a forecasting equation of the precipitation of the Southwest vortex and tried to forecast the weather and received good results.