The underwater acoustic transducer plays an irreplaceable role in the underwater communication process. The entire process of underwater acoustic communication can be summarized duo to the instructions from the PC to the modem. After being amplified by power amplification, it is sent to the underwater acoustic transducer, and the underwater part is received in the reverse direction. The selection of the underwater acoustic communication frequency and the selection of the underwater acoustic transducer were studied. The performance test of transducer was carried out to determine the carrier frequency of the underwater acoustic communication. The study of underwater acoustic transducers will provide a high guarantee for the stability and reliability of communication in the maintenance of  underwater submarine oil pipelines.The submarine is detected by the sonar-underwater ear. The piezoelectric ceramic is the material to make the sonar. It emits ultrasonic waves and reflects when it encounters the submarine. after being received and processed, you can measure the position, distance.