A high-resolution tidal model for coastal sea adjacent to Zhoushan was established based on the unstructured grid, Finite-Volume，primitive equation Community Ocean Model (FVCOM). The model simulation results were in good agreement with observational data, suggesting that the model can well reveal the tidal characteristics in the sea area. Tidal current energy in the Xihoumen Channel of Zhoushan was estimated based on model simulation results, the optimal location for power station was determined and the annual mean effective tidal energy at the location was also analyzed. The results show that the tidal current in the channel is dominated by alternating tidal current and the annual mean velocity and annual maximum velocity are greater than 1.2 m/s and 2.6 m/s, respectively. The annual mean and annual maximum energy flow density are greater than 1.2 kW/m2 and 6.5 kW/m2，respectively. The spatial distribution of the current velocity and the energy flow density in the channel are similar, both has three peak areas with values increase from the northwest to the southeast. The seasonal distribution of the current velocity and the energy flow density in the channel exhibits similar. The velocity and the energy flow density reach their maximum value in January, and are moderate in April (spring) and October ( autumn)，smallest in July (summer). Considering the tidal current energy resources and the criteria for selecting the power station site，the northwest cape of Cezi Island is then selected as the optimal power station site in the Xihoumen Chanel. The total average power and effective power at the selected site are 30.0 MW and 4.5 MW，respectively. Compared with existing power stations, the power generation capacity at the selected site is much larger and has great development potential.