Abstract: Using NCEP 1°×1°re-analysis data to analyze circulations character on heavy rain in Sichuan basin on 28th June 2009.The results show that firstly,the atmospheric circulations were relevant to high through of Baikal lake region,low vortex of Yunnan region and plateau shearing in 500 hPa.When heavy rain occurred,the cold through of Baikal lake region moved towards Sichuan basin and affected Sichuan basin.In 700 hPa,Southwest wind speeded up in Xichang and there was a meso-scale rain cloud-mass exiting in heavy rain region.Secondly,the physic diagnoses show that variation of local vorticity was essential to development of rain system,in through region,variation of local vorticity was plus.While heavy rain occurred,through appeared in north of Sichuan basin,during heavy rain time,there was plus variation of local vorticity in rain region in 700 hPa,plus variation of local vorticity was also important to development of rain system,and plus variation of local vorticity appeared in north of Sichuan basin firstly,then appeared in heavy rain regions,lastly heavy rain moved toward south of Sichuan basin.To some extent,when the area of plus variation of local vorticity was coincident between 500 hPa and 700 hPa,it was favorable for the formation of heavy rain.Therefore,plus variation of local vorticity was useful physic factor to judge rain areas.Thirdly,-βv was important to development of southwest in Xichang region.