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　0.5642　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.