Comparing the total pollution load into rivers in 2005 with the one in 2000, the analysis suggests that the percentage of point sources in total kept reducing year by year, and the non-point sources increased significantly, especially total phosphorus (TP) whose amount of pollution from non-point sources have already exceeded that from point sources. The total amount of pollution from non-point sources was almost equal, but its composition changed. The pollution from rural domestic sewage ranks first and the pollution from aquaculture and fields ranks second in the total amount of pollution from non-point sources. Based on the analysis of causes of non-point sources pollution, this essay gives some suggestion on the control of non-point sources pollution in plain river network of Taihu Basin.