Abstract:  The treatment to the water pollution of Chao lake is the requirement of national develop,pment strategy in China. This paper introduced the four kinds of reasons such as the longtime polluter accumulation, longtime polluted water accumulation, gradually disappeared wetlands and swamp and higher content of phosphorus in lake bottom as inner phosphorus releasing source, resulting in the water of the lake polluted. The polluters from point and non-point source pollution to the lake water mainly contained phosphorus and nitrogen elements. Research showed that the heavy polluted area located in the northwest part of the lake, while the lighter in the southwest part. The polluter accumulated during flood season, and dissipated into the Yangtze River after flood. According to the strategy of source control, the eight projects like road and bridge construction, flood control, channel and rive regulation, ecological rehabilitation, ecological agriculture, sewage interception and tourism development. To protect the project launching well, the effective working mechanism and assurance system were created and used to guide the next phase project scientifically.

Key words: lake treatment, pollution control, ecological pilot district