Baishakou Tidal Power Plant was built at the mouth of the barrier-lagoon where sand accumulated markedly in the front of the dam. In this paper, distribution characteries of sediments and mineral, erosion and accumulation variation of topography movement of sand acted by wave and transport rate of sand along coast were investigated. Results show that sand accumulation is the result of retransportion and redeposition procceses of sand in this region The main cause is the decrease of ebb tidal current and the increase of wave action since the tidal power plant was built.In order to ensure the safety of the tidal power plant, author suggests to extend appropriately the spur dike.