Based on the analysis of routine monitoring data of water quality in the front of Bailong lake dam,the paper constructed a two-dimensional water quality mathematical model for Bailong lake waters so as to simulate ammonia nitrogen, total nitrogen, total phosphorus, COD water quality of Bailong lake,and predict and analyze the change trend of water quality during the planning period. The results show that water quality indexes of total nitrogen and total phosphorus will continue to decline in 2016.According to the condition of current emissions in Bailong lake area,it proposed some schemes such as the social and economic control, prevention and control engineering of pollution source, ecological conservation, ecological environment regulation engineering,and decreasing plan of pollutant. It predicted water quality, every indicator was steadly enhanced,especially the total phosphor would enhance from class IV to class II.The implementation of the above four programs for the protection of existing water quality in the Bailong Lake has important significance, which has a very good reference for the protection of the similiar type of lake.