Abstract: In rapidly-urbanizing areas, contradictions between rapid development of the industry, high density of the population and backwardness of the sewage drainage facilities are quite outstanding. A river inside the Guandu Park, which is a heavily polluted river typical of the Guanduli District, Suzhou, was selected as a subject of study. Based on the analysis of characteristics of the district’s sewage system, specific manifestions and influencing factors of point pollution sources, non-point pollution sources and inner pollution sources in the area were summarized systematically, and amounts of various types of pollutants discharged into the river from the various pollution sources were investigated and estimated. Results show that the amount of COD_cr, NH₃-N, TN and TP discharged into the river reached 222.54,11.16,16.63 and 2.56 t•a^-1, respectively. Analysis of the sources for contribution rate indicates that industrial waste was the highest in pollution loading and followed by domestic sewage and rainfall runoff. Based on the above-discussed analysis and estimation, some countermeasures and suggestions are put forward for pollution control of the rivers in South Jiangsu, by taking into account the characteristics of the rapid development of urbanization in that region.