The 2-D tide control formula is resolved by Galerkin weighted margin method of finite element number,and the 2-D finite element mathematic model is founded and applied to Haian bay which is characterized by relative small calculation area and complicated boundary.The calculation result of tide numerical simulation for Haian bay is as follows:the numerical value and course of calculation’s water level and fluid velocity are accordant with the actual situation,the trend of fluid field is coincident to the past research,the new model uses different nonstructural grids,which has stronger adaptability to the complex engineering area and boundary comparing to that by the former model.As for the engineering problems of the small calculation area and complex boundary,the research result proves that the calculation precision can be improved by the tide control formula of finite element numerical dispersing equation.