Abstract: To solve the security problems in the process of switching networking technology to Voice over Internet protocol of dispatching switching network, this paper first analyzes the security risks and existing security protection measures of IMS and soft-switched network. Based on the analysis of the weakness of the existing security protection measures, this paper proposes an active defense security strategy of IMS and soft-switched network based on reinforcement learning under the intrusion response system. This strategy guides the devices in the network to take corresponding actions according to the running state to deal with network security problems, and the decision-making process is completed by the mechanism of reinforcement learning. The calculation results show that the active defense security strategy of IMS and soft-switched network based on reinforcement learning can play a flexible role in proactive defense against different types of attacks.