Abstract: Ecological operation is a measure of environment protection to balance eco-benefit and other benefits. When a conflict exists between these benefits in reservoir operation, ecological risk degree can be chosen as a decision-making basis for the operation. This paper presents an ecological scheduling model that is based on the hydraulic demands of fish spawning habitat under different ecological risks and the constraints of flow depth and velocity at typical downstream cross-sections of the dam. We use this model to evaluate the ecological risk degree of the spawning ground for Cyprinus carpio rubrofuscus Lacepede at the Yuanjiang Qiaotou hydropower station, and compare five typical daily operation schemes. The results show that the risk degree is zero for two schemes and above 0.5 for the other three schemes. And nine optimized schemes are obtained through optimizing these three schemes with three given target risk degrees of 0.14, 0.29 and 0.43. Comparison shows that the optimized schemes require a reduction in actual power generation with the reduction ratio in a range of 16.29% - 36.37%. Thus our model is able to balance power generation benefit and eco-benefit in the design of ecological scheduling schemes of reservoir operation.