Abstract: With the rapid social and economicdevelopment in Tonghai County,the bearing pressure of water environmental is increasing,and the restricting effect of water environment on social and economic development is also becoming more and more significant. In order to effectively analyze the carrying capacity of water resources in Tonghai County,a one-dimensional model was used to analyze the water environmental capacity of Qilu Lake,and its environmental monitoring data were also referenced. The results showed that although the nutrient level and water quality of Qilu Lake have decreased in recent years,it is still in the state of moderate-eutrophication. Domestic sewage and agricultural non-point source pollution are the main reasons,and the carrying capacity of water resources environment is still in the state of overloaded,and there is no environmental capacity at all. Without any improvement,it is difficult to eliminate the environmental pollution in a short time,and the water environmental capacity will remain overloaded for a long time. Finally,some countermeasures and suggestions were put forward to improve the water environmental carrying capacity of Qilu Lake.