Abstract:The increase of phosphorus concentration in water is easy to made ecological problems such as the algae multiply greatly. Phosphorus load reduction has always been the key work of water environment treatment. Focusing on phosphorus load reduction and takes the Shahe reservoir basin upstream of Beijing Urban sub center as the research object, the SWAT model is used to analyze the effect of 24 items source control process interception ecological restoration measures of 4 categories on phosphorus load reduction. The results showed that: (1) The reduction efficiency of total phosphorus is in the order of withdrawing from livestock and poultry breeding> decentralized sewage treatment> ecological bank protection> grass ditch, vegetation buffer zone> urban runoff control> saving medicines and fertilizers, and improving the understory structure. The benefits of source control measures such as withdrawal from livestock and poultry breeding and decentralized sewage treatment are very significant. (2) It is recommended to adopt 5m wide ecological ditches, orchard: a vegetation filter belt with a filter belt area ratio of 10:1, no herbicides, a 50% reduction in the amount of organic fertilizer, a 100% resource utilization of aquaculture waste, and a 30% reduction in the amount of sewage measures to reduce the agricultural production process phosphorus load generated. Reduce the phosphorus load generated by urban non-point source pollution by increasing the pervious paving rate by 20% and increasing the dispersive pollution treatment rate by 40%. The river is recommended to adopt high-coverage ecological bank protection and 5m wide river buffer zone. (3) Reduce the phosphorus load of agriculture-towns-rivers in space, and systematically manage the major ecological elements of mountains-rivers-forests-farmlands-lakes-grasslands. After the measures are implemented, the total phosphorus load reduction rate can reach 53%, and the area of watersheds with total phosphorus reaching the IV standard will increase 8.6%, the effect is particularly remarkable.