To analyze the efficacy of eco-operation of Three Gorges-Gezhouba cascade hydropower plants (so called Three Gorges Cascades) and its impact, the objects for the ecological operation of Three Gorges Cascades were designed to ensure the basic ecologic flow in the downstream channel, improve river-lake connection and protect biodiversity. In light of these objects, an eco-operation approach via man-made flood based on regular operation was presented.  The eco-operation by different methods were simulated to investigate the efficacy of eco-operation under typical inflow conditions. The simulation results also revealed the interaction among different objects as well as the impact of man-made flood on flood regulation and power generation. The study would be referential for the practice of eco-operation of Three Gorges Cascades.