Abstract: Taking the Shitouhe reservoir for example,this paper describes the principle and method of decision support system of optimum operation of reservoir for multi-purpose reservoir in detailed,and develops a decision support system of optimum operation for the Shitouhe reservoir.The system consists of 10 subsystem such as data collecting and transmitting,data management,hydrology forecast,drawing up using water plan,drawing up normal operation regulating plan,drawing up anti-flood operation regulating plan,making decision of normal operation regulating,making decision of antiflood operation regulating,optimum operation regulating and system maintain.