Abstract: An Comparative Analysis of circulation situation,environmental conditions,trigger mechanism,anomaly characteristics of the water vapor condition,surface energy and vapor pressure's characteristics in two Extreme Heavy Rain Processes during 8 to 11 and 17 to 19 July 2013 in Sichuan basin is performed by using of the NCEP / NCAR 1°×1° reanalysis data,FY- 2E satellite observational data and ground intensive observational data. The results showed that:(1) The two heavy rainfall processes occur in the situation of east high west low on 500 h Pa,and the heavy rainfall appears on the vortex's right side,the south airflow's left side,the high jet entrance area's right side.(2) The warm moist air is continuous transported to the sichuan basin by the south airflow on the edge of subtropical high,the environmental conditions of high energy,high humidity and stratification instability are formatted,and the plateau low system induces the formation of the vortex,all they make the convective system develop strongly; the position of subtropical high,low vortex and convergence zone,and the distribution of the basin energy and water vapor condition difference are the main reasons for the different rainfall distribution in the two process.(3) The anomaly characteristics of the water vapor conditions are obvious in the two heavy rainfall processes,especially in the process of "7. 8- 11".(4) The initial convection mainly appears in the significant incremental area of the ground vapor pressure during 24 hours and the low side of energy front,the evolution's trend of the ground vapor pressure also has certain instruction significance to intensity and persistent time after the heavy rainfall begin.