Generation　characteristics　of　L(0,　2)　mode　are　theoretically　studied,　the　reflected　acoustic　field　is　recorded　on　different　circumferential　positions　and　decomposed　into　a　L(M,　2)　modal　cluster,　numerical　dispersion　compensation　technique　has　been　employed　to　implement　a　time-space　transform　of　the　decomposed　signals,　and　the　defect　imaging　is　achieved　with　the　transformed　signals.　In　order　to　restrain　circumferential　guided　waves,　the　selection　of　exciting　sources　is　studied　by　FE　and　the　results　are　used　to　set　the　distribution　of　elements　in　a　transducer　array.　The　configuration　method　of　exciting　and　receiving　piezoelectric　wafers　is　studied　to　achieve　the　imaging　algorithm.　The　validation　of　the　algorithm　is　experimentally　verified　using　pipes　through　thickness　cracks　and　dual-defects.　The　results　show　that　the　method　can　locate　the　axial　and　circumferential　position　of　cracks　and　can　be　used　as　the　technical　foundation　of　pipe　health　monitoring.