Ultrasonic　wireless　power　transfer　(UWPT)　is　an　important　branch　of　wireless　power　transfer　(WPT)　technology,　which　is　widely　used　in　closed　metal　containers　for　charging　and　implanted　medical　devices.　But　for　an　underwater　UWPT　system,　there　are　two　main　factors　that　restrict　the　transmission　efficiency.　One　is　the　electrical　matching,　which　can　be　achieved　through　a　resonance　compensation　circuit.　The　other　is　the　acoustic　matching,　it　needs　to　be　considered　in　terms　of　transducer　structure　and　material,　which　has　not　yet　formed　a　complete　theoretical　system.　This　paper　proposed　a　design　concept　and　firstly　designed　the　material　and　structure　of　a　typical　ultrasonic　transducer　according　to　acoustic　transmission　matrix.　The　input　impedance　and　resonant　frequency　were　then　calculated　based　on　Mason　equivalent　circuit　model.　In　order　to　restrain　the　radial　acoustic　radiation　of　the　piezoelectric　ceramic,　a　new　iron　shell　was　added　to　the　designed　structure　and　formed　a　modified　transducer.　Then,　the　simulation　and　experimental　verification　were　carried　out.　The　theoretical　efficiency　of　the　modified　transducer　was　78.2%　when　the　transmission　distance　was　10cm　and　the　receiving　end　was　connected　to　a　200　load　resistor.