Abstract: This paper analyzes the characteristics of extreme precipitation changes in Baihetan Hydropower Station using the daily precipitation data from 1960 to 2019,and points out that extreme precipitation,extreme precipitation days and extreme precipitation ratios in Ningnan and Qiaojia counties are on the rise. The extreme precipitation threshold in Ningnan is 42.9 mm,and the average annual extreme precipitation days in Ningnan and Qiaojia are similar,2-3 days. Extreme rainfall peaked in June and the next in July. Using ERA5 reanalysis data,the physical quantity diagnosis and analysis of the typical "6.28" Hehetan rainstorm process is carried out,and it is concluded that during the occurrence of this strong convective rainstorm weather process,the flux of Baihetan Hydropower Station has strong convection of low-level water vapor,and the accumulation of water vapor provides conditions for the maintenance of heavy rain. The vertical velocity field shows strong vertical upward motion,while the hypothermia of the troposphere decreases with altitude,reflecting the instability of the atmosphere and providing favorable conditions for the local generation of strong convective precipitation weather. From the sudden heavy rain disaster in Baihetan,the enlightenment to meteorological services should change from a forecasting service model that pays sole attention to "process" to a tracking service model that pays attention to the process.