Abstract: A mixed integer convex cost minimizing model is built to determine the optimal ship speed at which the voyage cost is kept minimum under the condition of satisfying the emission requirements. The model, with the ship speed for given shipping line as the decision variable, calculates the cost per voyage according to the nonlinear relation between the cost and the influencing variables, such as sailing time, number of ships and fuel consumption. The Asia-Europe shipping line is examined with real power and capacity data of container ships in the fleet. The sensitivity analysis is performed to check the impact of sailing distance in restricted zone and the time penalty in a voyage. Experiments show that establishing control zone is effective in sulfur emission reduction but not in carbon emission as for global total emission is concerned. Under given schedule constraint, a ship reduces speed when sailing in Sulphur Emission Control Area（SECA） and increase speed out of SECA is a reasonable strategy to get balance between the voyage cost and emission requirements.