Based on the monitored water quantity and total phosphorus concentration of surface runoff in the Huashan Watershed in Chuzhou City of Anhui Province, this paper investigated the time distribution characteristics of the total phosphorus concentration and its output load, analyzed the ratio of maximum output load to the annual load in different consecutive days. The results show that the variation of the total phosphorus concentration during a year corresponded with rainfall runoff, and the total phosphorus concentration in flood season is generally higher than that in non-flood season. The total output load of watershed presented pulse type characteristic, which mainly concentrated in flood season and raining period. The calculation results show the ration of output load of total phosphorus to annual output load reach more than 50%, even in annual time less than 10%.