The　propagation　characteristics　of　L(0,　2)　mode　in　curved　pipes　are　investigated　theoretically　and　experimentally　for　the　purpose　of　defect　detection　in　curved　pipes　by　using　ultrasonic　guided　wave.　With　experiments,　transmission　coefficients　of　L(0,　2)　mode　in　90°　curved　pipes　with　different　curvature　radii　are　tested.　Results　show　that　mode　conversion　phenomena　happen　and　their　amplitude　attenuates　consequently　when　L(0,　2)　mode　propagates　in　curved　pipes,　and　propagation　distance　and　capability　of　defect　detection　are　effected.　Furthermore,　transmission　coefficients　of　L(0,　2)　mode　decrease　while　curvature　radii　increase.　When　excitation　frequencies　increase　in　the　same　curved　pipe,　transmission　coefficients　decrease.