Simulation is the basis of planning design and optimal operation of tidal power plan. In this paper, a method of simulation modeling is proposed. At first a real plant is abstracted as an ideal model. Then, the ideal model is divided into different unit model by the method of modularization and hierarchy. After every unit model has been verified, we get an accurate model of a tidal power plant. The simulation of jiangxia tidal test power station was presented to prove the efficiency of the proposed method.