Based on Vine Copula, which can accurately describe the correlation between highdimensional variables, and considering the spatial correlation of shortterm runoff forecasting errors, a risk estimation model for shortterm power generation scheduling of cascade reservoirs was constructed. The model was applied to the Xiluodu, Xiangjiaba, and Three Gorges reservoirs in the upper reaches of the Yangtze River, and the shortterm power generation scheduling risks of single reservoirs and cascade reservoirs caused by runoff forecasting errors were analyzed. The results show that the joint distribution based on Cvine Copula can better describe the error characteristics of daily runoff forecasting at Pingshan Station, Zhutuo Station, Cuntan Station, and Wulong Station. As the adjustable safety range of the reservoir increases, the risk rates of insufficient power generation and water abandonment in a single reservoir decrease, and the risk rate of insufficient power generation, joint risk rate of water abandonment, and cooccurrence risk rate of cascade reservoirs decrease. That is to say, the larger the regulating capacity of the reservoir, the smaller the risk it bears.