The nesting module of FVCOM is widely utilized in numerical simulations for both nearshore and offshore. However, the details of the nesting module on computation accuracy and efficiency have not been quantitatively assessed. In this study, we take Xiangshan Bay as a case study area and design two groups of experiments to examine this issue on tide simulation. The results indicate that nesting module effectively incorporates all tidal information from the open ocean through the boundary. The nesting module experiment successfully simulates the tides almost exactly similar to the original tides, while achieving an efficiency improvement of approximately 48% by avoiding computations outside the high-resolution area.