Abstract: To reduce the loss caused by spatio-temporal heterogeneity of rainfall and designed rainstorm to Wenchuan County, and reveal the spatio-temporal distribution characteristics of rain fall and the characteristics of designed rainstorm in Wenchuan County, based on the GPM satellite rainfall data from 2001 to 2020,Mann-Kendall method are used to analyze the spatial and temporal changes of rainfall in Wenchuan County from time scales of year, month, flood season, day and different scales of magnitude, and Stochastic Storm Transposition(SST)method is used to analyze the frequency of designed rainstorm.The results show that:(1) the annual total rainfall in Wenchuan County shows a significant growth trend, which is mainly affected by the rainfall changes in the flood season.(2) The spatial distribution of rainfall is uneven.Light rain is mainly distributed in the southwest of Wenchuan County, and moderate rain to rainstorm is mainly distributed in the east of Wenchuan County.(3) The designed rainfall results obtained based on SST method are reliable; with the increase of rainfall duration, the designed rainstorm center has a tendency to move from the southwest to the central and eastern part of Wenchuan County; the spatial non-uniformity of the designed rainstorm is more significant for small return period.The research results can provide reference for rainstorm and flood control in Wenchuan County.