Taking Zhushi rapids in the Minjiang river for example,we analyze the impacts of large-scale sand dredging on the riverbed evolution and channel conditions of rapids at the curved channel.The riverbed erosion of Zhushi rapids maintained a balance before the sand dredging.The riverbed erosion balance was destroyed and the riverbed dropped severely after the sand dredging.The severe siltation happened from the upstream to the downstream in the flood season.The impacts of large-scale sand dredging on the channel conditions are destroying channel boundary,reducing river water level,increasing upstream water surface slope,etc.The original stable curved channel was abandoned due to the lack of water depth.Waterway changed to go unstable straight channel,which created difficulties for the channel maintenance.Sand dredging also resulted in disordering of riverbed topography and big cross-flow in waterway,which is dangerous for the ships sailing.