Abstract: Water environment risk assessment is the basis of water environment pollution prevention and risk management. Based on the current situation of the main rivers into Baiyangdian Lake in the upper Baiyangdian Basin,considering the risk sources,river characteristics,physical geography and social development conditions,water pollution control ability and other factors,the water environment risk assessment system of the rivers into Baiyangdian Lake in the upper Baiyangdian Basin is constructed,the water environment risk of the rivers in the upper Baiyangdian Basin is evaluated by using the improved analytic hierarchy process（AHP）and the weighted summation method of comprehensive index. The results show that:in 2017,the overall risk level of the rivers into Baiyangdian Lake in the upper Baiyangdian Basin are in medium risk level,and some sections of Xiaoyi River are at the high risk level;evaluation indicators such as the proportion of environmental protection investment in GDP,the amount of chemical fertilizer applied per unit of arable land,and the current water quality of the river are the main factors that affect the water environmental risk level of the rivers into Baiyangdian Lake in the upper Baiyangdian Basin.The main measures to improve the water environment of the rivers in the upper Baiyangdian Basin include increasing the proportion of environmental protection investment in GDP,properly dealing with the relationship between economic growth and agricultural non-point source pollution,reducing the application intensity of chemical fertilizer and strengthening river governance. The research can provide reference for the treatment and restoration of the ecological environment of the rivers into Baiyangdian Lake in the upper Baiyangdian Basin.