Abstract: High-quality hydrometeorological observation data is the basic support for meteorological and hydrological disaster monitoring, forecasting and warning, and long-term climate change trend analysis. To solve the problem of low spatial resolution of existing integrated precipitation data at the watershed scale, this paper uses ensemble Kalman Filter（EnKF） fusion algorithm to merge precipitation data from 33 ground stations and TRMM and CMORPH satellite products at the daily scale in Qingjiang River Basin, yielding the 0.05°×0.05° fusion precipitation production of Qingjiang River Basin i.e., MSAP. The Leave-One-Out Cross-Validation method is used to quantitatively analyze the satellite precipitation data, ground interpolation data and MSAP fused precipitation data. It is proved that the EnKF fusion algorithm can improve the precision of precipitation in Qingjiang River Basin from three aspects: correlation coefficient R, mean absolute error MAE and root mean square error RMSE. In addition, the fusion algorithm overcame the shortcomings of low accuracy of satellite data and ground data in part of the watershed boundary area, which shows that the EnKF fusion algorithm has application potential in precipitation data fusion. Furthermore, MSAP is compared with CMFD, ERA5 and MSWEP reanalysis data, and the spatial distribution of heavy precipitation events corresponding to the two largest flood peaks in Qingjiang River Basin and Yangtze River during the flood season in 1998 is analyzed.The results also show that the MSAP data has the highest R and the smallest MAE, RMSE in terms of the time scale. In terms of the spatial distribution of errors, the spatial difference of accuracy evaluation index of MSAP data in each site is the smallest, and the order of accuracy of the four kinds of reanalysis data from high to low is MSAP ＞ CMFD ＞ MSWEP ＞ ERA5. CMFD, MSWEP and MSAP can reflect the center of rainstorm to some extent in the process of 5-day and 2-day heavy precipitation events. In terms of spatial distribution and precipitation amount, MSAP and CMFD are basically consistent.