Abstract: On the basis of Poisson equation, a new triangular grid generation method is developed in this paper. In order to make the triangular grids in the model well fitted to the complicated boundaries of coastal engineering, the source terms in Poisson equation are selected properly for different subregions. This grid generation method is applied in the tidal model of Zhuang sea region, and the tidal currents before and after theconstruction of harbour and navigation channel are well reproduced and predicted respectively. The error in the modelling due to the nonideal grid generation is basically avoided.