Abstract: The multiobjective optimal operation of a five-reservoir system is studied. according to the characteristics of the reservoirs and the water users, a multiobjective mathematical model by stages of sequential optimization is established. The first priority objective of the model is to optimize water supply for users of two urban and three irrigated areas. The second is to optimize power generation of the hydropower station Al.The results show that satisfied multiobjective benbfits may be gained with the model.