Abstract: To ensure the water supply security of the North Hubei Water Resources Allocation Project and the drinking water quality for nearly 500, 000 residents, this study takes the drinking water source area of Fengjiangkou Reservoir as the research object. By integrating historical water quality data from 2018 to 2021 and conducting supplementary monitoring from 2023 to 2024, combined with the source intensity coefficient method, ECM model, and equivalent standard pollution load method, the current status of non-point source(NPS) pollution in the reservoir area, the amount of pollutants entering the river, and the characteristics of load contribution were systematically analyzed. The results show that the overall water quality of the reservoir area ranges from Class Ⅱ to Ⅲ, and the water quality of tributaries is generally worse than that of the main stream entering the reservoir (COD exceeding the standard is the most prominent in the wet season); Fengjiangkou River is the main tributary for pollution input, with its TP, TN, COD, and NH3-N inflow accounting for more than 58.99% of the total basin load; agricultural planting is the primary pollution source (equivalent standard pollution load ratio of 67.90%), followed by rural life (27.67%) and livestock and poultry breeding (4.42%); Shahedian Village, Zemin Village, and Tianhekou Neighborhood Committee are the core contribution units of pollution load in the two major basins. Based on the pollution source tracing results, targeted control measures are proposed from three aspects: source reduction, awareness improvement, and government supervision, providing technical support and typical cases for the prevention and control of non-point source pollution in drinking water source areas of southern mountainous regions.