Wireless Mesh Networks (WMNs) have many applications in homes,schools,enterprises,and public places because of their useful characteristics,such as high bandwidth,high speed,and wide coverage.However,the security of wireless mesh networks is a precondition for practical use.Intrusion detection is pivotal for increasing network security.Considering the energy limitations in wireless mesh networks,we adopt two types of nodes:Heavy Intrusion Detection Node (HIDN) and Light Intrusion Detection Node (LIDN).To conserve energy,the LIDN detects abnormal behavior according to probability,while the HIDN,which has sufficient energy,is always operational.In practice,it is very difficult to acquire accurate information regarding attackers.We propose an intrusion detection model based on the incomplete information game (ID-ⅡG).The ID-ⅡG utilizes the Harsanyi transformation and Bayesian Nash equilibrium to select the best strategies of defenders,although the exact attack probability is unknown.Thus,it can effectively direct the deployment of defenders.Through experiments,we analyze the performance of ID-ⅡG and verify the existence and attainability of the Bayesian Nash equihbrium.