Through　the　investigation　and　analysis　of　the　status　and　influence　factors　of　post-earthquake　disaster　on　urban　transport　system,　this　paper　studied　the　influence　of　the　bridges,　roads　and　roadside　buildings　after　an　earthquake　on　the　optimum　path　searching,　put　foreword　a　principle　of　post　earthquake　optimum　path　analysis　based　on　the　level　of　road　passage　probability,　road　availability　length　and　road　width.　A　decision　information　system　has　been　developed　which　has　the　ability　of　transportation　system　management,　optimum　path　analysis　and　searching　using　the　network　analysis　model　of　ArcGIS　Engine.　On　the　needs　of　earthquake　disaster　relief　the　system　can　analyse　and　simulate　the　optimum　path　for　the　command　and　rescue,　relief　material　transport,　fire　fighting　dispatching,　ambulance　dispatching　and　shelter　path　indication.