The cause of the heavy rainfall occurred in central Yunnan Province from June 30,2002 is analysed with the MICAPS data, GMS satellite images and the echo data of Doppler Weather Radar 3830 C.It is found that this heavy rainfall process is caused by cold vortex and mid low level shear. The heavy rainfall region is corresponding with the strong ascending region of vertical speed and vorticity, and accompanied with the high energy and high wet regions. There is a developing mesoscale cold vortex cloud cluster from the satellite image. Furthermore, the radar echoes show that some obvious mesoscale systems (for example: mesoscale convergence line, mesoscale cyclone, anti wind area, etc.) with typical convective characteristics occurred during this heavy rainfall process.