Abstract: A multirobjective optimization model for operating cascade hydropower stations is established.The model can maximize both firm power and annual energy production simultaneously.The model is solved using the strength Pareto differential evolution(SPDE) approach.The latter is a novel extension of the Differential Evolution (DE) algorithm to multirobjective optimization problems.SPDE adopts the fitness assign method used in the strength Pareto evolution approach 2(SPFA2)，andmodifies theDE operators according to the characteristic of multir-objective optimination.An adaptive Cauchy mutation (ACM) is also used to prevent premature convergence.The model is tested using a case of Three Gorges cascade hydropower stations.The result shows that SPDE is able to simultaneously consider the two optimization objectives and effectively dealwith complex constraints.A setof alternative non-dominated schemes with uniform coverage can be provided for decision making, which presents a viable alternative formultirobjective optimal dispatch of cascade hydropower stations.Our result could be used as a reference formaking the midbmg teffn generation scheduling schemes for Three Gorges cascade hydropower stations.