Abstract: After the high-frequency transducer is connected with a long cable, the resonant frequency drifts away from the operating frequency, and the admittance value at the working point deviates greatly from that without the long cable, which causes impedance mismatch between the transducer and the transmitter and receiver. In this paper, the characteristics of the high-frequency underwater acoustic transducer with long cable are studied. By establishing the equivalent circuit model of the transducer and using the transmission line theory, the four port matching network is designed and simulated, and a matching circuit board is made. The experimental results show that the tested system matching performance is consistent with the simulation calculation, which improves the electromechanical conversion efficiency of the system, and proves the feasibility and engineering practicability of this method.