At present, the increase of intercity railway trains has made it more convenient for passengers to travel. However, in the face of constantly adding trains, the work of traditional manual preparation of train working diagram has become very difficult. The rapid development of artificial intelligence technology makes it possible to optimize the train working diagram by intelligent means. In this paper, based on the existing intelligent adjustment strategy using the Sarsa algorithm, an optimization method for intercity railway train working diagram using the improved Sarsa algorithm is proposed. The proposed method adopts a differentiated optimization strategy for peak and off-peak hours to solve the tradeoff problem between train evenness and operation costs. The experimental results show that the proposed strategy can reduce passenger waiting time and train operation costs by 20.00% and 67.80%, respectively. Moreover, compared with the Sarsa algorithm for improving balance and reducing conflict severity in previous studies, the proposed strategy can not only reduce the train operation costs, but also reduce the waiting time of passengers by 12.12%.