Different reclamation types to be used for the tidal flat have different hydrodynamic influences on the bay. Numerical experiments based on the land reclamation (LR) and the mariculture reclamation (MR), respectively, are conducted for the same reclamation project in the Shuangpantu, for quantitative comparisons. Results show that the MR has less influence on the hydrodynamic environment than the LR. The difference is more than 50％.