Utilizing the conventional meteorological data, NECP 1°×1° reanalysis data, surface precipitation and Fujian CINRAD/SA data, the cause of the heavy rainfall over the western Fujian Province after Saola Typhoon landing is analyzed. The results show that the northerly flow of Continental High Pressure led to the southward movement of Saola’s upper vortex. When the typhoon entered the large environmental vertical wind shear zone, the typhoon tilted to the left of the shearline, which made typhoon move more southward. The south tilting structure provided favorable dynamic condition over heavy rainfall region. The water vapor transportation supplied by Typhoon Saola and the typhoon’s southwest airflow provided sufficient moisture for the heavy rainfall. The cold air intrusion at upper levels and warm and moist air at low levels induced the conditional instability, which was favorable for the development of deep wet convection. Warm advection combined with velocity convergence, the incursion of dry cold air at upper level, warm and moist air at low levels, and the establishment of the southwest jet at lower levels were three mesoscale systems favorable for the severe rain.