This　article　analyzes　the　loads　of　the　duo-servo　brake　and　builds　the　key　brake＇s　rear　tip　model.　On　the　basis　of　this　model,　it　builds　one　domestic　vehicle　duo-servo　brake　finite　element　model　and　analyses　its　working　stress　by　using　the　CAD/CAE/CAM　software　I-DEAS.　The　result　shows　that　the　tip＇s　stress　is　greater　than　its　limited　value　and　the　improvement　way　is　to　weld　two　boards　in　the　tip＇s　two　sides　to　lower　the　tip＇s　stress.