Abstract: Based on high altitude and ground real-time data and satellite image, the rainstorm process in Tongliao of Inner Mongolia from 20^th to 23^rd in July, 2012 was analyzed, furthermore basic physical conditions for rainstorm generation were discussed. Results showed that： high altitude was controlled by low vortex and ground was affected by cyclone, which were circulation background of the rainstorm; higher low-rise positive vorticity was benefit for the generation and development of convective weather, and was the important trigger mechanism of rainstorm in Tongliao; the pumping action of upper-level divergence and low level convergence strengthened ascending motion, and was benefit for formation of the rainstorm; the rainstorm had close relationship with specific humidity of 850 hPa and 700 hPa; the position of high-level jet and low-level jet as well as their couolin~ effect were very imoortant for the formation of rainstorm.