Experimental　defect　detections　in　curved　pipes　was　carried　out　by　using　ultrasonic　guided　wave　technique.　Different　kinds　of　defects　including　artificial　circumferential　defects　and　structural　defects　were　detected　using　longitudinal　mode　L(0,　2)　at　certain　frequencies　excited　by　length-expanding　and　contracting　piezoelectric　elements　distributed　uniformly　along　circumferential　direction　in　90°　curved　pipes.　Effects　of　circumferential　defect　dimensional　variations　on　waveform　amplitudes　reflected　from　the　defects　and　the　ends　were　analyzed.　Multi-defect　detection　in　curved　pipe　was　studied　as　well.　Experimental　results　show　that　ultrasonic　guided　wave　inspection　technique　can　be　used　to　detect　defects　with　different　positions　and　types　in　curved　pipes.　Useful　exploration　is　done　to　detect　defects　in　more　complicated　pipe　system　using　ultrasonic　guided　waves.