Abstract: In order to design a key distribution scheme with security,expandability,validity,fault tolerance and usability for the wireless mesh networks,the authors present a key distribution scheme using a combination of techniques,such as zone-based network topology structure,virtual CA(Certification Authority),offline CA,threshold structure and identity-based cryptosystem.The author also analyzes the performance of the key distribution scheme in theory and simulates the key distribution for the backbone network with OPNET software.The following conclusions are drawn:The variation of the key distribution delay in the best condition of the different scales is between 0.4 s and 0.7 s,and the most key distribution delay is about 0.5 s;Under the worst condition,the key distribution delay increases gradually,and the variation of key distribution delay is between 0.4 s and 4.8 s;The average key distribution delay is 0.564 2 s; The successful rate of the key distribution is a percentage of 100 when the number of the backbone router is less than 30,and the successful rate of the key distribution is a percentage of 94 when the number of the backbone router is 32.