Abstract: Bailian River Reservoir is one of the key drinking water sources in eastern part of Hubei Province. With the economic development and the repaid improvement of urbanization level in this basin, water quality of Bailian River Reservoir has been degraded within the last decades, which seriously affected the water safety in this basin. As one of the main pollutants, total phosphorus (TP) should be controlled strictly in Bailian River Basin. This study used data sets of land use and agrotype from the 2011-2021, and performed simulations for the spatial distribution characteristics of TP load in the Bailian River basin. Moreover, the unit area loading index method was used to identify critical source areas and to simulate the effect of Best Management Practices (BMPs) on the reduction of TP load in the Bailian River basin. Results revealed that: (1) The TP load in Bailian River basin was higher in the downstream areas than upstream, with the critical source areas located in Fangjiazui Township and the three sub-basins with higher agricultural activity intensity. The three sub-basin areas accounted for 1.7% of the total basin area and 24.9% of the TP load in the basin; (2) The average annual TP load in the Bailian River basin from 2018-2021 was 180.17 t/a, and the TP source areas showed apparent spatial discrepancies, with the subbasin located in Fangjiazui Township demonstrating the largest average annual TP load of 18.9 t/a. (3) Among the single BMPs, the most two efficient reduction in TP load were the “vegetated buffer strip with an area ratio of “5% between fields” and “2 km river grassing”, which had reduced by 50.5% and 50.2% of TP load, respectively. The integrated BMPs are effective in reducing TP load intensity, particularly in critical source areas, with 60.9% reduction of TP load. This study provided a scientific reference for using the integrated BMPs to reduce the TP load in the Bailian River basin.