We　present　defect　detection　of　polyethylene　(PE)　pipes　by　using　active　infrared　thermography　technique.　A　finite　element　model　was　built　to　mimic　the　transient　heat　transfer　in　PE　pipes,　in　which　constant　heat　flux　boundary　condition　was　applied　to　the　inner　surface　of　the　PE　pipes.　Various　defects　with　different　diameters　and　depths　were　simulated　in　PE　pipes　and　they　would　affect　the　thermal　distributions　from　which　the　relation　between　thermal　images　and　defect　sizes　and　locations　would　be　established.　An　electrical　heating　bar,　as　the　novel　thermal　excitation　source,　was　employed　in　active　infrared　thermography　experimental　system.　The　finite　element　simulation　results　are　well　agreed　with　the　one　obtained　from　the　infrared　imaging　experiments　and　it　demonstrated　that　finite　element　numerical　method　can　be　an　effective　method　to　analyze　infrared　imaging.　Furthermore,　defects　in　heat　fusion　joints　of　PE　pipes　were　fabricated　and　detected　by　the　developed　active　infrared　thermography.　The　experiment　showed　that　active　infrared　thermography　based　on　an　electrical　heating　bar　could　provide　a　novel　tool　for　nondestructive　evaluation　of　PE　pipes.　©　(2014)　Trans　Tech　Publications,　Switzerland.