Abstract: Many traditional security technologies such as intrusion prevention and intrusion detection are subject to restrictions in the network environment of mobile ad hoc networks can not achieve the desired results. This paper introduces mobile agents in wireless ad hoc network security model, designs a distributed intrusion detection and respond system. Through a variety of functions of mobile agent the system implements the functions of intrusion detection intrusion, and uses mobile agents to track, isolate invasion node to make a timely response. Experimental results show that this method can save the resources of node and avoid the collapse of the network, effective in detecting and preventing intrusions.