Air-coupled　ultrasonic　testing　technology,　possessing　the　characteristics　of　non-contact　and　non-destruction,　is　widely　used　in　nondestructive　detection　for　materials.　An　air-based　line-focus　air-coupled　ultrasonic　transducer　was　designed　and　fabricated　according　to　the　measurement　of　crystalline　silicon　solar　cells.　Compared　to　the　ultrasonic　transducer　based　on　the　traditional　polymer　matrix,　the　air-based　line-focus　air-coupled　ultrasonic　transducer　adopted　the　3D　printing　method　to　hollow　out　the　polymer　matrix　frame,　which　will　further　reduce　the　acoustic　impedance　of　piezoelectric　composites.　The　center　frequency　of　the　transducer　is　about　150　kHz,　and　the　focus　radius　is　20　mm,　aperture　is　28　mm.　The　generating　and　receiving　performance　of　the　transducer　was　measured.　An　crack　detection　experiment　was　implemented　on　a　monocrystalline　solar　cell　by　air-coupled　Lamb　waves.　The　crack　can　be　located　by　analyzing　the　amplitude　of　the　received　signals,　furthermore,　a　correlation　analysis　was　performed　to　extract　the　characteristics　of　the　cracks.　©　2018,　Editorial　Office　of　Acta　Materiae　Compositae　Sinica.　All　right　reserved.