Sun Moon Lake in recent years because of tourists continues to increase, that goes along with volume of water pollution also increased. The information of water quality of CTSI values rise again. After opening to the mainland china tourists to Taiwan in recent years, with the number of tourists doubled, the water quality are growing bad with the amount of pollution. The water pollution in Sun Moon Lake cannot be ignored. According to the investigation, WuJie channeled water from the upper Jhuoshuei River into the lake were the major pollution sources. Except of the major pollution sources there are many wastewater treatment plant surrounding in the Lake, such as Shueishe, Sunmoon wastewater treatment plant and other hotel’s wastewater treatment plants. The more effluent discharged from the plant and less in the water quality in the region. Carlson’s Trophic State Index are showing eutrophic state near the Hanbi peninsula. In this project we used Vollenweider model to analysis the Sun Moon Lake Reservoir assimilative capacity of various types, and based on characteristics of the lake catchment area was divided into four water pollution hot spots, respectively, to assess the sources of water pollution hot spots that can carry the capacity and meet Water proposal to reduce the amount of each category. And used WASP model to build another lake water quality model, based on model results indicate that the current assimilative capacity of the BOD and NH3-N to Sun Moon Lake were approximately 2,100 and 950 kg / day, and by the Sun Moon Lake watershed point sources and non-point sources the average daily contribution of pollution BOD and NH3-N emission of about 67.3 and 23.4 kg / day, while the BOD contribution of water from the Wujie about 3,400 kg / day, NH3-N contributed about 734 kg / day. Assessment indicated that the number of days of some of the current Sun Moon Lake BOD load exceeding the assimilative capacity, NH3-N of the load is not exceeded the assimilative capacity of water bodies. Simulation results show that if the Wujie channeled water reduced more than 40% in the amount of pollution, lake water would meet water quality standards. This project also used linear programming to help solve the best benefits management plan to reduce the pollution. It proposed water pollution hot zone Ⅰ, Ⅱ, Ⅲ required to build the eco-engineering, artificial floating islands area to be 1,080 ~ 1,765 m2, the length of the catchment area grass ditch about 610 m ~ 971 m.