Abstract: In order to improve the forecasting and service ability of heavy rainfall in Tianshui，based on of all automatic station data, sounding data and Micaps actual data, he author analyzed a heavy rainfall weather process occurred in August 12, 2010 in tianshui. Results indicated that the heavy rain occured associated with the vortex shear line in the south of Gansu Province. The moisture transports coming from the SCS to Tianshui was main sources of the heavy rainfall process and the moisture transports from the Qinghai-Tibet Plateau and upstream of Indian Ocean played complementary roles. The coupling interaction of the high and low-level jet had a certain guide and promote role in the heavy rainfall process. Upper air divergence and the flow field of low convergence situation caused strong upward movement, which was a necessary condition for the heavy rainfall. According to the analysis of the vertical velocity field, it was favorable to the occurrence and development of heavy rain as constant upward movement to trigger the release of unstable energy.