In this paper,  the Pareto strength SCE-UA algorithm (PSSCE) is presented to handle the reservoir optimization operation problem.  The approach treats the constrained optimization as a two-objective optimization: one objective is the original objective function; the other is the degree of constraint violation.  SCE-UA algorithm is applied to the two-objective optimization by using the individual's comparing procedure and the population ranking procedure which are respectively based on the Pareto dominance relationship and the Pareto strength definition.  The new approach is more general,  effective and robust.