This paper proposes a centralized coordinated ramp merging control method for intelligent connected vehicles. First，a model of centralized coordinated ramp merging control is established. Then, the model is converted to a non-linear optimization problem through discretization，which can be solved by the NOMAD algorithm. Simulations with different randomly initialized merging conditions are performed to verify the effectiveness of the proposed method and to discuss the impact on fuel consumption. Besides，the proposed method is compared with the methods in existing literature，and the results show that the proposed method is effective under different initial merging conditions. Compared with the benchmark method，the proposed method reduces the average fuel consumption by 42.38%.