Abstract: Taking the rainstorm process from 20:00 to 08:00 on July 25, 2021 as an example, the actual weather, circulation background influence system and actual physical quantity field are analyzed, it is concluded that the rainfall weather process was mainly affected by the cooperation of the easterly system around the typhoon and the weak cold air on the ground. In the actual service, it played the role of meteorological early warning and prediction in the first line of defense for disaster prevention and reduction, but there were still some deficiencies in the prediction ability of business personnel, the construction of regional stations, public awareness and so on.