Abstract: A heavy rainfall event in Sichuan province on July 21-22,2012 is preliminarily analyzed based on the version 2.0 of gridded China ground precipitation datasets (0.1 degree resolution),the Hourly FY-2E Temperature of Black Body (TBB) datasets provided by the China Meteorological Science Data Sharing Service,and the Six-hourly gridded (0.1x0.1) ERA-Interim atmospheric reanalysis datasets (including temperature,wind field,geopotential height,and relative humidity) from European Centre for Medium-range Weather Forecasts (ECMWF).It reveals that the Southwest Vortex activity provides the beneficial atmospheric circulation conditions for this heavy rainfall in Sichuan Basin.Based on above conditions,the subtropical high guided warm moist air and the southward Siberia cold air are converged in the Sichuan Basin,together with the generation of wind shear,the release of a large amount of unstable energy accumulated in the eastern Sichuan Basin,and an updraft is formed over the basin,which can provide favorable weather conditions for the precipitation process.With the eastward movement and weakening of the Southwest Vortex,this heavy rainfall process in Sichuan Basin terminates.