Abstract: When applying Genetic Algorithm(GA) to the problem of reservoir operation,the new chroms created by genetic operations are often infeasible and needed to revise.In cascade reservoirs operation,however,such revision becomes complicated because of the hydraulic and electric connections between time sequences and reservoirs.Therefore,an advanced GA—Genetic Algorithm Successive Approximation(GASA)—is proposed in this paper.Firstly,the possible optimum is obtained by traditional GA without modifying any infeasible alternatives,then a new research space is formed by adding or subtracting a value to the optimum,and new times of optimization are then carried on in altering new spaces until the conditions for procedure ending are satisfied.The advantage of this algorithm is that it can do optimizing within a space including feasible and infeasible schemes,which is attractive in the optimization of such complicated systems as cascaded hydropower plants.A simulated example is also provided,and the results are compared with those obtained by Discrete Differential Dynamic Programming(DDDP) and Progressive Optimality Algorithm(POA),which indicates the feasibility and validity of GASA.