The　purpose　of　this　paper　is　to　study　the　propagation　mechanism　and　damage　monitoring　and　evaluation　of　ultrasonic　guided　waves　in　steel　cylinder　concrete　pipes　based　on　the　array　PZT　sensing　system.　The　method　is　to　use　ABAQUS　finite　element　software　to　establish　the　mechanical　electrical　coupling　finite　element　model　of　array　PZT　and　steel　cylinder　concrete　pipes　with　different　damage　degree,　and　carry　out　numerical　simulation　for　crack　detection　of　steel　cylinder　concrete　pipe　by　piezoelectric　wave　dynamic　method.　The　result　of　the　study　is　to　put　forward　the　damage　index　and　establish　the　relationship　between　the　damage　degree　and　the　damage　index;　the　amplitude　of　the　piezoelectric　signal　received　by　the　steel　cylinder　concrete　pipe　without　damage　is　the　highest;　with　the　increase　of　the　damage　crack,　the　loss　of　the　signal　at　the　crack　is　greater;　the　damage　index　of　the　transmission　signal　is　calculated　based　on　the　energy　method,　and　the　quantitative　relationship　between　the　damage　degree　and　the　damage　index　is　determined.　The　assessment　level　of　damage　index　is　no　damage,　slight　damage,　medium　damage,　serious　damage,　replaceable　pipeline　and　serious　damage　cannot　be　used.　The　conclusion　is　that　the　suggested　damage　index　of　steel　tube　concrete　pipe　structure　can　reduce　the　occurrence　of　ground　collapse　caused　by　pipeline　leakage.　©　2021,　Editorial　Department　of　Journal　of　SJZU.　All　right　reserved.