Based on the precipitation data of 10 national automatic observation stations in Tongren from 1981 to 2020 in the past 40 years, this paper calculates the multi-time scale standardized precipitation index (SPI), determines the degree of drought and flood, analyzes the spatial and temporal distribution characteristics of drought and flood, and selects typical drought and flood years Perform circulation analysis. The results showed that: (1) Tongren City was generally droughty in the 1980s and flooded in the 1990s. Tongren City presents alternating droughts and floods in summer. (2) Droughts are relatively frequent in the central, western and northeastern parts of Tongren City, and gradually weaken to the surrounding areas; the frequency of rain and waterlogging in the central, western and southeastern parts of the city is relatively high, and the northwestern part is the lowest. The droughts and rains in the summer is mainly mild and moderate, with very few cases of extreme severity. (3) In summer, the mid-high latitudes of Europe and Asia are negative anomalies of geopotential height. In drought years, the geopotential height anomaly centers of the Ural Mountains and northeastern China turn to positive anomalies. (4) The El Ni?o phenomenon in the equatorial Central and Eastern Pacific and the anomalous distribution of SST in the South and North Pacific are closely related to the occurrence and development of Tongren summer waterlogging; the La Ni?a phenomenon in the equatorial Central and Eastern Pacific, the Indian Ocean and the Western Pacific SST anomalous distribution affect Tongren"s summer bias. The occurrence and development of drought are closely related.