Abstract: The Xinghua bay, located in the west of Taiwan Strait, has a large scale of reclamation and dredging works which will directly have impacts on the hydrodynamic environment. Based on the hydrological measurement data of February 2009, studies of characteristics of tidal level, current field and residential field with and without works are conducted by using the method of tidal harmonic analysis and current harmonic analysis, and a tidal flow mathematical model. As the analysis results show, in the Xinghua bay, the tide is a regular semidiurnal tide with subtle shoaling while the tidal current is a regular semidiurnal shallow current. From the outside to inside, the tide wave which is composed of stable direction tides of the Xinghua waterway and Nanri waterway has some characteristics of the standing wave, and the spring tide is dominants in the Xinghua waterway while the ebb is dominant in the Nanri waterway. After completion of works, the forecast tidal process lines of July 2013 based on the harmonic constants are in good agreement with the observational ones, and at the same time the characteristics of tide and current are kept the same. Velocities within the harbor and channel increase slightly. The tide fluxs of both the Xinghua waterway cross section and Nanri waterway cross section decrease, as well as the tidal prisms. And the Eulerian residual current field remains unchanged in the whole bay while the vortexes in the entrance areas are strengthened.