Abstract: In this paper a one-level complex terrain mesoscale model was used to diagnose numerically severe convection weather occurred in the Yangtze River valley area on 10 May 1989. The results show that dynamic and thermodynamic effects of the mesoscale topography play an important role in the course of heavy weather, It is especially noticeable that local circulations of mountain-valley or slope winds and lake-land breezes caused by different heating of terrain have key influence on occurrence,intensification and movement of severe convection storms.