Significant variation of flow condition of Yibin to Luzhou reach is affected by unsteady flow caused by hydropower stations in the Jinsha River and the mainstream and tributary of Minjiang River.Based on one-dimensional unsteady flow mathematical model and analysis of measured data,study on the propagation process of unsteady flow from Yibin to Luzhou and the change of hydraulic parameters relative to steady flow condition is achieved.The results show that the wavelength of representative unsteady flow is about 218 km,propagation velocity is about 3 m/s;as the propagation distance increases,the attenuation amplitude decreases and the waveform becomes smoother;downstream flow decrease along the river when the water level of Yibin is at the crest,the trough is just opposite;relative to constant flow condition,the flow change in the range of 0 m3/s to 730 m3/s and the water level rises from 0.5 m to 2 m,the average velocity of cross section varies from -0.5 m/s to 0.2 m/s,the variation of water surface slope is from -0.2‰ to 0.2‰ and the maximum gradient is 1.38‰.