Abstract: Based on the data of conventional observation ,surface hourly precipitation,reanalysis data from NCEP,as well as the satellite and radar date,the heavy rainfall event occurring in northeast Chongqing regionon 7 June 2010 was analyzed focusing on the circulation background,the intensity and location of the evolution of low-level jet and the water vapor and the heat transports by low-level jet.The result show that southwest low-level jet strengthening and moving to north caused the formation of southwest vortex, and heavy rain occurred when the closed circulation of southwest vortex was formed and frontal zone θse was promoted by the southwest low-level jet over Chongqing, so that rainstorm area got plenty of heat and moisture supply.It had obvious convergence at low level and the divergence at high level in the heavy rainfall areas;Heavy rainfall occurred after the arrival of strong low-level jet corresponding to the wind speed increase and downward extension brought by jet stream,and the precipitation was increased as the increase of speed of southwest wind.