Abstract: Forthe purpose of improving the information security protection capacity of communication-based train control system while facing sophisticated information attacks,a quantitative method for attack and defense of train control system wasestablished anda proactive defense mechanism was designedbased on game theory. Firstly, the information security risks of train control system were analyzed from three aspects including access, equipment and communicationaccording to network architecture and application characteristics of train control system, so as to reveal the basic types andmethod of attacks.Then the attack-defense quantization method was established with the consideration of attributes of both attack means and targets. And themulti-stage attack-defense game model was built on the basis of stage characteristics ofattacks. Finally, the proposed model was verified by simplified attack-defense behavior database. The results show that the model proposed can outputattack-defense strategies under rational conditions.

Key words: train control system, information security, proactive defense, game theory, attack-defensequantification