Lamination　is　one　of　common　defects　in　the　manufacturing　process　of　seamless　metallic　pipes.　In　this　paper,　the　interaction　between　the　circumferential　Lamb　waves　and　lamination　in　the　midplane　of　an　aluminum　pipe　is　studied.　The　used　circumferential　Lamb　waves　are　CL0　and　CL1　modes　generated　with　a　finite　element　method　code.　Lamination　along　the　circumferential　direction　is　established　by　the　demerging-node　method.　Numerical　results　of　arrival　time　are　compared　with　theoretical　results　in　order　to　verify　the　accuracy　of　the　excitation　ways.　The　interaction　between　circumferential　Lamb　waves　and　lamination　in　a　damaged　full　circular　pipe　is　analyzed　by　composing　the　received　waveforms　of　the　corresponding　receivers　when　CL0　and　CL1　modes　are　excited　at　different　excitation　positions:　the　inner　subpipe,　the　outer　subpipe,　and　the　main　pipe.　The　composed　waveforms　fit　well　with　the　original　waveforms.　When　CL0/CL1　mode　reaches　the　entrance　and　exit　of　a　lamination,　it　generates　new　mode　and　undergoes　multiple　reverberations,　diffraction,　and　mode　conversion　between　the　two　ends　of　the　lamination.　Based　on　the　detailed　analysis　of　the　waveform　in　detail,　some　phenomena,　which　are　different　from　those　in　a　plate,　are　observed.