Xiangjiaba hydropower station in the Jinsha river has a big installed capacity.During operating,it will cause downstream unsteady flow which makes the big water level variation amplitude,and thus influence seriously the waterway maintenance management of Yibin to Chongqing reach of the Yangtze River. Based on the long river unsteady flow mathematical model,we study the development of the unsteady flow,analyze the influence of the daily regulation of waterway maintenance,and put forward corresponding maintenance management measures.