The　linear　eigenvalue　buckling　analysis　and　nonlinear　buckling　analysis　using　finite　element　software　ANSYS　has　been　carried　out　on　the　stability　of　cylindrical　shells　with　8　kinds　of　stiffening　rings,　the　instability　mode　and　load-displacement　curve　of　ring-stiffened　cylindrical　shells　subjected　to　external　pressure　are　given.　The　results　showed　that,　linear　eigenvalue　and　non-linear　buckling　analysis　shows　similar　trend,　though　with　error.　The　stability　analysis　should　be　carried　out,　after　linear　eigenvalue　method　is　employed　to　the　stiffening　ring　optimizing　in　the　design　of　cylindrical　shell.　Among　angle　steel,　T　profile　steel,　flat　steel,　half-tube　and　II　profile　steel　eight　kinds　of　stiffening　rings,　II　profile　steel　has　the　most　best　strengthen　effect　to　cylindrical　shells,　and　try　best　to　keep　the　centroidal　axis　of　stiffening　ring　away　from　the　vessel　wall　when　fixing　the　stiffening　ring.