The　problem　of　buckling　stability　is　very　important　in　thin-walled　cylindrical　shell　structure.　In　order　to　investigate　the　buckling　phenomena,　digital　image　correlation　(DIC)　method　was　applied　in　this　experiment.　The　specimens　have　a　thickness　of　0.131mm　and　the　ratio　of　external　diameter　(R-0)　to　thickenss　(H)　R-0/H　is　252.　Due　to　its　curved　and　thin　walled　elements,　measurement　of　displacement　and　strains　by　using　the　traditional　methods　is　difficult,　because　there　is　not　enough　space　of　sticking　necessary　torsion　gauges　to　measure　the　out-of-plane　behaviour,　even　if　it　is　possible,　the　rigidity　of　the　gauge　itself　will　have　an　effect　on　the　buckling　strength.　However,　by　using　the　optical　image　correlation　method,　the　problem　is　solved.　DIC　method　is　an　optical　instrument　which　utilizes　the　full-field　and　non-contact　measurement　to　gauge　the　three-dimensional　displacement　and　strains　on　materials　and　structural　parts.　In　this　paper　three　dimensional　digital　image　correlation　system　is　applied　to　observe　the　buckling　generation　process　in　details　and　make　a　record　of　the　surface　displacement　during　the　compression　test　by　using　two　high　resolution　digital　cameras,　then　the　test　data　are　analyzed　and　compared　by　a　special　correlation　technique　which　can　determine　the　surface　displacements　of　cylindrical　shells　and　it　is　shown　in　colour　contour　in　full-field　region.　The　buckling　strengths　obtained　by　the　theoretical　and　experimental　methods　are　compared　and　discussed　in　this　paper.　The　experimental　study　shows　that　the　buckling　strength　of　theoretical　value　is　much　higher　than　that　of　experimental　one,　because　the　buckling　strength　is　highly　dependent　on　the　imperfections.