This paper discusses the impacts of bay mouth reclamation on the inland sea and channel from three aspects:tide,tidal flux and water change.Results show that the two projects have little influence on the inner bay.For Jin’gu River,reclamation narrows the channel width,decreases the flow velocity and diminishes the tidal flux by 17%.The half-exchange period is extended by 1.21 days.Lao-ren sand enclosure can strengthen the tidal volume of east channel but has little influence on Jin’gu River,because the narrowing of Jin’gu river may diminish the water diversion ratio.Though bay mouth reclamation partially takes up the middle channel,it has little influence on the inner bay,which means future reclamation planning can be considered the middle channel and beaches on its both sides.