Runoff and soil losses from agricultural fields were investigated as the major non-point sources of phosphorus entering Yanghe reservoir.According to rainfall characteristics of Yanghe watershed in recent years,the phosphorus export by surface runoff from gentle slope was studied under simulated rainfall and analyzed rainfall data conditions.The results showed that the soil phosphorus losses of Yanghe watershed relied mainly on particulate phorphours;the content of different forms phosphorus of surface rainfall in Yanghe watershed was wheat-corn continuous cropping>high-yield cron cropping>low-yield corn cropping>secondary shrub;with the increase of rainfall intensity,the content of particulate phosphorus increased slowly but that of ortho-P decreased;with the plant cover degree increasing,the content of particulate phosphorus and TP of surface runoff decreased slowly but that of ortho-P increased slowly.