Phosphorus transport form slope cropland of purple soil at natural rainfall and simulated rainfall events were compared in this study.The results showed that,there were two process: overflow and subface flow.Runoff dynamic course were influenced by different rainfall intensity and crop coverage.The variation of rainfall intensity led to phosphorus moving through subface flow and resulted in eutrophication of local water.The flow charge of overland was bigger than the subsurface flow in both events,then exported different phosphorus loads.