Abstract: Based on various multi-source meteorological data including Radar mosaic reflectivity data, the three-dimensional structure and evolution characters of radar echo related to the precipitation process triggered by the southwest vortex occurred during July 30 to 31 in 2009 were analyzed. The main results are as follows, 1.There are inconsistencies between the intensity of the southwest vortex and the precipitation, and the most heavy rain occurred before the southwest vortex is at its strongest. 2.The genesis and development of the mesoscale convection systems are the important factor of the precipitation related to the southwest vortex. The mesoscale convection systems and the southwest vortex are independent but interplay to each other and the precipitation are the result of the interactions. 3. The strongest combined reflectivity factors are occurred before the southwest vortex is at its strongest too. The intensity and the types of the radar echo related to the precipitation in the basin are obviously influenced by the southwest vortex.