Abstract: Using of conventional meteorological data and infrared cloud image data, the causes of rainstorm weather process was analyzed in Hulunbuir on July 14-16, 2013. The results showed that： the circulation situation of the precipitation was the situation of rainstorm of the interaction with typical subtropical high and westerly trough, system of exuberant vertical development and steep slope, made the lower layer system to be always in the ascending motion area; The rainstorm resulting triggering mechanism was surface cyclone convergence and the line lifting; The low-level jet created favorable conditions for the development of convection, and low-level jet provides everfount vapor transport for the rainstorm; The corresponds conrresponded very well between convective cloud strong developed of south for thousands of kilometers banded cloud and drop zone of heavy rain.