Abstract: This paper aims at the shortage of water resources and the increasingly prominent social and ecological problems in the irrigation area of Fenhe reservoir. Taking the minimum water shortage in irrigation area as the goal, the optimal allocation model of water resources in Fenhe reservoir irrigation district is established, and a multi-objective calculation method for water right and ecological water demand is proposed.The long series dispatching calculation of Fenhe reservoir is carried out by the model, the calculation results of simulated operation of Fenhe reservoir in different level years are obtained, and the optimal allocation of complex water resources in the project area is solved. By solving the model, it can be seen that the domestic and industrial water use in the Fenhe irrigation district is basically satisfied, and the agricultural water demand is greatly alleviated.