In order to solve the problem of water resources shortage in the Western mining area of China and make it reasonably and effectively allocated, the optimal allocation model of water resources was established based on Water Evaluation and Planning System in this paper. This model simulated the water resources changes of 8 scenarios from 2015 to 2035. These scenarios are consisted of different economic growth, population changes, water saving and greening intensity. The optimal development scenario applicable to the mining area and the water resources allocation results corresponding to the scenario were determined by calculating the comprehensive benefits of society, economy and ecology. The results show that the optimal development scenario for the mining area is high-speed economic growth, powerful water saving and moderate greening. Under this scenario, the total water demand of the mining area will reach 39.73 million cubic meters by 2035, the demand shortage will be 1.7 million cubic meters, and the water shortage rate will be 4.28%. The water resources allocation result corresponding to this scenario can be used as a reference for decision makers, which can provide a scientific basis for the rational use of water resources in the Western mining area.