Abstract: Based on the hourly precipitation data of meteorological observation stations in Sichuan Basin from June to August (2007—2019), the ERA5 reanalysis data and the cumulative precipitation forecast data for 1 to 10 days from 00:00 of ECMWF model in Tigge Data Distribution Center, the prediction ability of ECMWF model for total precipitation, accumulated rainstorm water, rainstorm days and rainstorm intensity in Sichuan Basin was evaluated. 170 rainstorm cases in Sichuan Basin were selected based on the precipitation observation data, and the objective circulation classification of 500 hPa geopotential height field was carried out by using K-means clustering method. The rainstorm in Sichuan Basin was divided into 3 types and the TS scores of each type were calculated. The causes of the difference in predictability of each type of rainstorm were preliminarily analyzed. The results show that: (1) The total precipitation forecasted by ECMWF model in Sichuan Basin is more, the accumulated precipitation and the number of rainstorm days are less, and the intensity of rainstorm is weaker; With the increase of forecast time, the total precipitation, the rainstorm accumulative precipitation and the number of rainstorm days gradually increase. The intensity of rainstorm has no obvious upward and downward trend. The model has many empty reports of small and moderate rainfall, and there are omissions of rainstorm rainfall. The center of heavy rain accumulation is mainly formed by more precipitation frequency rather than larger precipitation intensity. (2) The objective classification of rainstorm in Sichuan Basin can be summarized as the whole basin type, the east basin type and the west basin type. The optimum forecast time of rainstorm in whole basin type and east basin type is 1~4 days, and that in west basin type is 1~3 days. During the period of 1~10 days, the lowest TS value of the whole basin type and the east basin type is 6~7 days, and that of the west basin type is 4~5 days. In the period of 6~8 days, the rainstorm forecast effect of the west basin type is the best. The TS score of the whole basin type is higher than that of the east basin type. (3) The circulation pattern at 500 hPa and the wind field and specific humidity at 850 hPa in Sichuan Basin are closely related to the TS score, which may be the main factors affecting the rainstorm forecast in Sichuan Basin.