Based on the C-band data of new generation weather thunder, radiosonde data and precipitation data of regional automatic stations in Tongren City, the heavy rainstorm weather process from June 29 to 30, 2020 is analyzed and studied.The results show that the weather process is a heavy rain in the western section of the shear line of the Yangtze River Basin, which is mainly affected by the 500 hPa low trough, 700 hPa and 850 hPa low vortex shear, and ground convergence line, strong low-level convergence, high-level divergence, high and low altitude, the configuration and topographical uplift of Fanjing Mountain stimulated the heavy precipitation. The convective effective potential energy in the atmosphere increases rapidly before the rainstorm, which provides unstable energy for the rainstorm. The analysis of radar echo characteristics shows that the precipitation is mainly generated by local echo. The mixed precipitation echo of stratocumulus gathers and moves stably over Bijiang and Jiangkou, showing a "quasi static state". The echo propagates backward, and there are multiple echo units merging with each other. During the period of heavy rainfall, the echo of ≥ 35 dBz generally extends to over 8 km, there are several strong echo center nuclei in the middle and low layers, and there are upwind areas existing and maintained for a long time.