The impacts of tideland reclamation on hydrodynamic environment near estuarine area were reviewed and evaluated. The hydrodynamic environment in the engineering water region can be changed by tideland reclamation, resulting in re-adjustment of the original stable river bed. Vast sediment accumulation can lead to the development of land area toward the sea, and coastlines can be altered. The effect of storage and dissipation of tidal energy by tidal flat can be lost, and the tidal range can be changed. Estuaries can be constricted and wetland orphology can be destructed by large scale reclamation, leading to possible reduction of flood discharge capacity of rivers and flood disasters impacted on surrounding towns. It is proposed that system evaluation should be performed for the impacts of tideland reclamation on hydrodynamics, estuary and coastline changes, flood and tide prevention so as to guide the efficient utilization and protection of tideland.