Based on the implications of optimal allocation of water resources with water-saving as a priority, the idea of water-saving priority, water demand depending on water supply, and forced industrial patterns are proposed. The current water-saving level is analyzed and assessed, the planning year’s water-saving target is determined, and the water demand under saving conditions, which reflects the planning year’s water demand, is forecasted according to the industry quota method. The feasibility of the proposed method was verified through its use in optimizing the allocation of water resources in Taizhou City, in Yuhuan County of Zhejiang Province. The results show that the model of water resources allocation based on the idea of giving priority to water-saving can significantly improve the efficiency of water resources utilization and enhance the sustainability of the water resources utilization.