Radar echo feature of a heavy rainfall event is discussed on the basis of analyz ing NEXRAD products during the mesoscale-β heavy rainfall convective system e vent in June 18th, 2006 occurred in Yongding City. Conclusion is drawn as follow s: largescale circulation, ample water vapor and stronger ascending movement ar e advantageous weather background of severe rainfall. The results of show that severe rainfall is led by local convective echoes strengthening a nd integrating; lowermiddle layer cold advection triggers the strong convectio n. And convective cells show typical features of severe precipitation system. Co nverse wind region and good vertical movement strengthens the development of con vective cells. The server largerscale rainfall area moves along the same direc tion as echoes do, which cause socalled “train domino effect". Furthermore, s ystem moves slowly, which helps severe rainfall continue.