A computational method for the ocean ship routing based on optimization theory is presented in this paper. In the computational programme “breaking circle method” is used, by which a principal contradictory line can be obtained in the operations research. The automatic selection of calculating network and the initial values have been realized. The quantitative estimation for the change of navigating speed under the different conditions of ocean wave and current has been done. The objectivly quantitative computational method is provided for ocean ship routing and forecast service following ship tracks. The calculating examples and practical experiments of ships have proved that this computational method is highly effective. A computational method for the ocean ship routing based on optimization theory is presented in this paper. In the computational program “breaking circle method ” is used, by which a principal contradictory line can be obtained in the operations research. The automatic selection of calculating network and the initial values ​​have been realized. The quantitative estimation for the change of navigating speed under the different conditions of ocean waves and current has been done. The objectivly quantitative computational method is provided for ocean ship routing and forecast service following ship tracks. The calculating examples and practical experiments of ships have proven that this computational method is highly effective.