Aimed at the problem of water eutrophication in Xi'an Expo Park artificial lake that occurs as a result of mismanagement,the paper used EFDC hydrodynamic model and WASP water quality model carried out the simulation research on 79 hectares film waterproof artificial lake system in Xi'an Expo Park under four situations such as changing water quality, discharge and so on.Experiment shows that only used for artificial lake ecological water requirements without considering the minimum directly-filling water of systemic circulation, nutrients will accumulate in 120 days because of slow water velocity and eutrophication occur in the lake.When the circulated direct replenishment is controlled in the scope of 1 m3/s,the pollutant accumulation phenomenon can't be effectively changed at “dead zone” of hydraulic condition badness in thel lake. The effect of minimum standard water is more obvious than that of minimal direct replenishment.The effect of standard replenishment water with circulation is the best in four scenarios simulation. Research suggests that the longest economic security days is 120d in the artificial lake of Xi'an Expo Park.The water ecosystem in lake must be constructed so as to improve itself purification capacity.