Reclaimed water is an important supplement to conventional water sources. The use of recycled water to replenish rivers and lakes is of great significance to improving the water ecological environment and alleviating the contradiction between supply and demand of water resources. Compared with traditional water resources, recycled water resources are subject to policy factors and ecological needs of rivers and lakes, and there is great uncertainty in their utilization and allocation. In response to the above problems, this article takes the Zhijiang area of Hangzhou as an example, and uses hydrological and ecological methods to calculate the ecological water demand of the river network, and combines policy factors and water quality conditions to analyze the feasibility and influence of using recycled water for ecological water replenishment. The results show that Zhijiang area has the demand for recycled water utilization, and its ecological water demand is about 211,300 m3/d. This result can provide reference significance for regional recycled water utilization.