This paper studied and explored the tide change caused by reclamation project by used of numerical simulation method. The applied mathematical model is a software of mathematical model of water flow and sediment by Tianjin University with intellectual property right. Taking the middle sea area between Tianjin port and Caofeidian port for example,it analyzed the change of tide characteristics in target sea area and other area, and mainly focused on the combined effect of reclamation works on Bohai bay. Finally come to some conclusions:the reclamation works make tide movement along the waters of Bohai Bay appear irregular change;the impact of coastal reclamation on coastal waters of Bohai Bay presents the performance of the increase of flow rate and the enhancement of tide power,and the impact of that in the offshore water is contrary;a single reclamation work has little effect on the overall trend of field in the Gulf.