On May 20, 2020, Shiqian County experienced the heaviest rain of the year. It is characterized by concentrated heavy precipitation period(from 2 o’clock to 7 o’clock), high intensity (maximum 72.2 mm/h) and wide coverage (the whole county). The article first explains the reasons for the heavy rain using the precipitation data from the CIMISS database. It is found that the “May 20” heavy rain in Shiqian was caused by the superposition of two rounds of short-term heavy precipitation, especially the second round of rainfall was sudden, strong and its time concentrated in 1 to 2 hours. The article then presents a detailed overview of the weather services provided before and during the heavy rain, and summarizes that strengthen on duty,, short-term and temporary monitoring, and targeted meteorological services can effectively make up for the shortcomings of weather forecasts. It also points out the problems in the meteorological services. Finally, the author expresses some thoughts on the accuracy of weather forecasts and early warnings, the timeliness of meteorological data, the monitoring ability of disastrous weather, the professional level of business personnel, the cooperation between stations and departments, and the publicity of meteorological services. It is hoped that this article can be a meaningful reference for future weather services.