Abstract: Based on the conventional observation data,precipitation data from automatic stations and NCEP 1°×1° reanalysis data from NCEP center,the contrast analysis for three torrential rain cases occurred in Sichuan Basin in summer 2013 is made. The results show that all three processes happened at a favorable circulation background,integrating with rich water vapor,strong vertical ascending motion,and unstable atmosphere stratification. The former two torrential rain occurred against the low- layer system of Southwest vortex,and the third process is shear- line. The water vapor and energy accumulate at the low- level,and accompanied by the increased ascending vertical velocity. The water vapor rising convergence is consistent with precipitation of greater value in the same area. The horizontal distribution of negative wet z- helicity at low- level correspond well with the heavy rainfall center of the same period of time. In the vertical distribution of the rainfall area,the favorable dynamic structure of the positive vorticity with water vapor convergence rotation in the low- level and negative vorticity with moisture divergence rotation in the high- level contribute to trigger the torrential rain.