Abstract: Using NECP reanalysis data and ground precipitation data, the continuous rain processes in Liangshan Prefecture from September 10 to 17, 2020 were diagnosed and analyzed. The results show that the continuous rain process affects the stability of the system from low to high levels. The southwesterly flow in the Bay of Bengal brings continuous water vapor and energy, and there are obvious water vapor convergence centers in the heavy rainfall area. The obvious upward movement in the middle layer provides lasting dynamic support for the occurrence of heavy rainfall. The continuous low-level cold advection provides favorable conditions for the intersection of cold and warm airflow, and the energy front area of the intersection of cold and warm air masses has a good indication for the demarcation of precipitation intensity.