We employ the 2D tidal current numerical model （MIKE21-HD） to build a current model in the Da-xiao-yushan water area，which is validated by observed data. In view of the complex tidal current conditions between islands in Da-xiao-yushan water area，the influence of the reclamation project on the surrounding hydrodynamic conditions is simulated by using the numerical simulation of the tidal current based on this model. The simulation results show：1）The influence scope of the reclamation project is mainly concentrated in the vicinity of the reclamation area，without affecting the hydrodynamic conditions of the large-scale sea area. The average tidal velocity change is basically within 0.5 m/s. 2）1.5～2 m/a siltation occurs in the weak current areas on the east and west sides of the reclamation area，and the seabed erosion and siltation rate in the remaining waters is basically below 1m/a. The reclamation project is feasible.