Abstract: Using the WRF model to simulating a rainstorm process occurred in Sichuan reduced by the southwest vortex activity from 20 to 22,July,2008,the article analyzes the effect of cold/warm air intrusion on the development of the southwest vortex,numerical results show that: the cold/warm air intrusion from north boundary can change streamline field in the middle and low troposphere.While reduceing temperature at north boundary,strengthening the northwest air current to going south,there is no southwest vortex in Sichuan,replaces it with a trough,simultaneously in the rain area the ascend movement weakens,the low level convergence to be weaken,the temperature in middle troposphere increases,specific humidity reduces,the rainfall area concentrates nearby the trough,the rainfall area and the intensity weaken obviously and they are smaller than the control test.Increasing temperature at the north boundary to cause northeast air transport to the south,the low value system moves southward,warming promoted the surrounding air convergence to the precipitation center,strengthened the middle and lower atmosphere convergence ascend movement,the temperature in middle troposphere and has been increased,rain belt move southward,the rainfall intensity strengthen obviously and they were great than the control test.Reduce or increase the temperature of the western boundary has relatively small effect on the flow field pattern,intensity and location of the vortex,cool makes the vortex northward,wind speed of troposphere increased and weakened area alternates distribution;warming makes the vortex eastward,the lower middle troposphere reduced but high-level wind speed increased,the two effects on the precipitation area is also small,has different effects on the intensity of heavy rain center.