At present,there is a bottleneck in the research of MEMS vector hydrophone.A large number of experiments show that there is a mutual restriction between the sensitivity and the detection bandwidth of the hydrophone.To ensure that the hydrophone has the detectable bandwidth of 20~500 Hz for long distance ship radiated noise,it is urgent to improve the sensitivity of MEMS vector hydrophone in low frequency detection. On the basis of the ordinary cilium MEMS vector hydrophone, this paper proposes to integrate the crosssector on the cylindrical cilium to increase the sensitivity of the low frequency detection by increasing the acoustic pressure receiving area.The sizes of the crosssector are determined by the ANSYS Workbench multiparameter optimization, and the optimized sizes are verified by ANSYS15.0.The micromachined method is used to integrate the crosssector and the cylindrical cilium,and the sensitivity of the crosssector cilium vector hydrophone is tested by the hydrophone calibration system.The results show that the sensitivity meets the growth trend of 6 dB per frequency range, and the sensitivity at 500 Hz is up to -183.6 dB(0 dB= 1 V/μPa), which is nearly 5 dB higher than that of the ordinary structure.