Based on the general characteristics and existing water resources problems of the Yellow River Irrigation Area, the water resources optimal allocation model considering the multi dimensional objectives of water resources, social economy and ecological environment is constructed, and the harmony evaluation index system of water resources is established. Then, they are applied to the second phase of Zhaokou Yellow River Irrigation Area Project. In the solution set of this model, four representative optimal allocation schemes are selected to analyze the benefits of water resources, social economy and ecological environment. And the scheme P4 is selected as the multi objective optimal scheduling scheme, which is then applied to the harmony evaluation and multi scheme regulation. The results show that the harmony degree of the irrigation area is significantly improved after model optimization. After the regulation of the indices with low harmony, such as groundwater exploitation rate, agricultural water use ratio, urbanization rate, grain yield per capita and green coverage rate, the harmony degree is further improved to 0.790.