The current modified Jensen wake model does not correct both the initial wake radius and the initial wake wind speed, and cannot accurately predict the actual wake wind speed of offshore wind farms. A three-time modified Jensen wake model was proposed based on the second modified Jensen wake model and was verified by wind tunnel experimental data from offshore wind farms. Secondly, considering the full wake and partial wake area, the three-time modified Jensen wake model was applied to the layout optimization of the offshore wind farm. The optimization variables were the coordinates and number of wind turbines and the optimization objective function was the cost of electricity. Then, the wind turbine layout of the offshore wind farm was optimized using salp swarm algorithm. The results show that the layout of the wind farm was more homogeneous used the three-time modified Jensen model than corrected Jensen model. Compared to a full tail flow layout, the cost of electricity is reduced by 2.16% when a partial tail flow layout is considered.