With the rapid development of urban rail transit and the need to promote high-quality development, higher requirements have been put forward for the operation and organization level. For the lines without overtaking facilities, it is important to improve the train speed by optimizing the train stopping plan. Based on the traditional A/B skip-stop mode, this paper proposes A/B/C skip-stop mode to achieve time-saver without transfers. Firstly，the characteristics of all trips under various stopping patterns are investigated, and an mixed integer programming model with stopping patterns and frequencies as decision variables are constructed. Additionally, a genetic algorithm (GA) is developed based on the model. Finally, the effectiveness of the proposed model and heuristic algorithm is verified through a set of real-life instances based on the Beijing Metro Line 6. The results show that the travel time and in-train time can be reduced by 2.15% and 6.79% respectively without transfers. If taking no account of waiting time, the in-train time can be reduced by 14.25%.