A new unsteady flow，with a wavelength of more than 200 km，has been formed at Yibin Hejiangmen by the convergence of daily regulated unsteady flow from Xiangjiaba Hydropower Station and Minjiang River，which has a significant impact on the navigation elements of the shoal channel of the Yibin-Luzhou river（Xulu section）. A two-dimensional unsteady flow mathematical model is applied to analyze the propagation law of the daily regulated unsteady flow on the channel elements of Shuanjianqi in Xulu section. The results show that：1）It takes about 1.5 hours to transmit the regulated unsteady flow from Hejiangmen to Shuanjiangqi. And the maximum daily variation amplitude of Shuanjiangqi water level is about 1.053 m，which is about 30% lower than Hejiangmen. The water surface gradient in the peak period is lower than that in the trough period. Sand mining in the pebble beach of Shuanjiang has a significant impact on the unsteady flow. 2）In the process of representative daily regulated unsteady flow，the river width of Shuanjianqi is 204~585 m that achieves the channel maintenance water depth standard of 2.9 m. Moreover，and the existing navigation mark setting at the channel boundary cannot satisfy the minimum maintenance water depth，so the existing navigation mark setting scheme needs to be optimized.