In this study, the DongPieHong Ditch were taken as the research object, five sampling points were set to measure the COD, NH3-N,TNandTPindexes. The correlation and principal component analysis were used to judge the main pollution sources and calculate pollution contribution rate. According to the population in the basin, the load of point source pollution into the river was estimated. As a result, the load of COD, NH3-N and TP into the river was 323.04t/a, 43.8t/a and 3.9t/a, respectively. According to the statistics of the rainfall in the basin, the concentrations of COD, TP and NH3-N in the initial rainwater were measured and calculated for non-point source pollution, and the results shown that the inflow loads of COD, NH3-N and TP into the river were 34.59t/a, 0.12t/a and 0.71t/a, respectively. It was found that the main cause of the pollution in the east flash flood gully was point source pollution, and the proportions of COD, NH3-N and TP into the river were 90.33%, 99.72% and 84.61%, respectively.