In view of the problems such as premature convergence and long running time of complex reservoir optimal scheduling algorithm, this paper studied the principle, method and procedure optimal operation of reservoir group based on extended linear quadratic gaussian algorithms (ELQG). It applied ELQG to solve the optimal operation model of Xin'an River reservoir and Fuchun River one and compared the dispatcher result under the optimum of different typical years with that of DP algorithm.The result showed that annual generating capacity of cascade reservoir joint calculated by ELQG algorithm reduced 10 to 30 million kW oh and the average water level decreased by 1.0 to 1.3m. The calculation velocity increase by nearly 20 times.ELQG algorithm has strong practicability and maneuverability,and can provide a new way for the optimal operation of multi-target and high-dimensional reservoir group.