nfluenced by the unsteady flow under the power station,the 30 km downstream area of Xiluodu has complicated navigational current conditions,which threatens the safety of ship navigation.Through the prototype observation,the propagation law of unsteady flow and its main influencing factors are investigated.The results show that the change of the water level in each dock is consistent with the trend of the discharge flow,the phenomenon of franking along the propagation is obvious,the propagation speed is fast.The average wave speed of Dahewan to Shunhe section is 11.2 m/s,and the water level variation and change rate at the Dahewan dock during the flood season are as high as 4.38 m and 1.21 m/h.The unsteady flow characteristics of the river channel below Xiluodu dam are related to the variation of the discharged flow rate,the change duration,and the water level of the Xiangjiaba reservoir,with the greatest response to the flow rate variation.When the discharge flow increases (decreases),the larger the variation amplitude of the discharged flow at the power station,the shorter the change duration,the higher (lower) the water level of Xiangjiaba reservoir,the faster the propagation of unsteady flow,and the larger the variation amplitude of the water level and the change rate of the water level of the dock.