Abstract: In this paper,a dynamic collaborative intrusion detection model based on multi-agent is defined,the collaboration mechanism between the detection agents and its security, communication mechanism between the detection agents and its security are analyzed and discussed.On the basis,the collaborative detection algorithm of this model is given.The hierarchical organizational structure of the detection agents facilitates the management and control of the collaborative detection;the coordination agents ensure the security of collaboration between agents by the locking operation before collaborative detection;the coordination agents ensure the security of communication between agents through authentication during communication.The collaborative mechanisms and security measures of this model improve the accuracy of the intrusion detection.