Abstract: Ecological operation is a new mode of reservoir operations, in which ecological factors are considered besides social and economic benefits. This article briefly introduced concepts of ecological flow and ecological operations. Then cases of ecological operations around the world before 2000 and during 2000~2019 were reviewed, and the future research was prospected. Ecological operation studies began with the concept of ecological flow in 1940s, then more than 200 methods including hydrologic method and hydraulics method were proposed to calculate the ecological flow. Current studies try to consider ecological factors into the reservoir operation, and previous ecological operations considering single-objective were replaced by multi-objective ones, including water quantity, water quality, sediments and aquatic resources regulations. Combined dispatching, cascade dispatching and layer-stratified water intaking dispatching were widely used in practice and achieved remarkable progress. Knowledge about mechanisms of ecological operations is still limited, though many studies have revealed that measures of engineering, biological or management could solve several problems. It is difficult to coordinate the contradiction between economic development and ecological by the empirical work alone. Therefore, it is necessary to develop mechanism-based ecological operation models in the future. In addition, it is urgent to quantify the effects of reservoir operations on aquatic ecosystems health.