Abstract: The design method of high-sensitivity piezoelectric copolymer cylindrical hydrophone was presented.The relationship between the material structure of poly(vinylidene fluoride-co-trifluoroethylene)P(VDF-TrFE) and its piezoelectric characteristics was discussed.Utilizing analytic method and finite element method,the influence of the multimode coupling properties on the sensitivity response of the piezoelectric copolymer cylindrical hydrophone was analyzed,while the hydrostatic pressure resistance and noise characteristics were simulated and analyzed.The piezoelectric copolymer cylindrical hydrophone outperformed the piezoelectric ceramic hydrophone and the piezoelectric homopolymer hydrophone of the same structure in sensitivity in low frequency range by 20 dB and 5 dB,respectively.The piezoelectric copolymer hydrophone sample with the dimension of Φ14 mm ×55 mm was eventually fabricated.The pressure sensitivity response of the copolymer cylindrical hydrophone was measured to be as high as-181.8 dB ± 1 dB in the frequency range of 10 Hz~1 kHz.Moreover,in this frequency range its equivalent self-noise pressure was lower than the sea ambient noise at zero level sea state.The measured results matched well with the theoretical model.The results revealed that this design significantly improved the receiving sensitivity of cylindrical hydrophones in low frequency range,and provided ideas to enhance their hydrostatic pressure resistance.