Dispersion　equations　of　torsional　modes　in　three　different　two-layer　pipes　are　obtained　by　means　of　analyzing　different　stress　and　displacement　boundary　conditions　of　these　structures.　It　is　found　that　the　orders　of　dispersion　equations　vary　with　these　pipe　structures.　All　these　equations　are　solved　numerically.　As　a　result,　torsional　mode　dispersion　curves　of　these　three　structures　are　shown　respectively.　Main　propagation　characteristics　of　torsional　modes,　especially　T(0,　1)　mode　are　analyzed.　Torsional　modes　in　these　different　structures　are　excited　and　received　using　thickness　shear　mode　piezoelectric　transducers　in　the　experiment.　Experimental　results　are　in　good　agreement　with　theoretical　results.　The　results　show　that　torsional　dispersion　equations　of　different　two-layer　pipes　can　be　developed　using　the　global　matrix　method,　and　their　dispersion　curves　provide　some　theoretical　guidance　of　mode　choice　for　defect　detection　in　these　pipe　structures.