Abstract: Phosphorus loss risk assessment is crucial for effective phosphorus loss management. Based on the Revised Universal Soil Loss Equation (RUSLE), a particulate phosphorus index model was constructed by combining soil total phosphorus content, phosphorus enrichment coefficient of particulate sediment, and sediment transport ratio. The distribution of particulate phosphorus loss in Linjiang River Basin in 2010, 2015, and 2020 was estimated, and the critical source areas were identified. The results showed that the maximum values of particulate phosphorus loss from non-point sources in Linjiang River Basin were 495.9, 815.8 and 936.1 kg/hm² in 2010, 2015 and 2020, and the average values were 0.8, 0.9 and 2.2 kg/hm², respectively. The critical source areas were identified based on the 2 kg/hm² threshold value for phosphorus loss from surface sources. The area of critical source areas was 86.7, 77.6 and 182.5 km² in 2010, 2015 and 2020, respectively, accounting for 11.8%, 10.6% and 24.9% of the watershed area, and contributed 84.7%, 92.0% and 92.6% of the particulate phosphorus loss from non-point sources. The critical source areas were mainly distributed in the low hills and gentle slopes of the upper Linjiang River, Shengshui River, Dazhu Creek and Jinmen River sub-watershed. To implement zoning management for the critical source areas, measures for controlling particulate phosphorus loss in Linjiang River Basin, mainly through fertilizer reduction and engineering interception, were proposed.