This paper designed and studied the threedimensional underwater acoustic sensing mechanism of MEMS vector bionic hydrophone based on piezoelectric effect，including modeling of basic structure , analysis of directional detection , basic research of devices fabrication and related test. The static displacement distribution and stress analysis of the device have been simulated by Ansys 15.0. With the help of scanning electron microscopy and atomic force microscopy,Pb（Zr0.53Ti0.47）O-3(PZT) piezoelectric thin film was observed. The frequency sweeping test and directivity test were carried out and the resonance frequency is about 500 Hz, the peakpeak output voltage value is 280 mV. The obtained results have a certain scientific and practical values for promoting the development of modern underwater acoustic sensing technology and solving technical problems such as high precision position, identification and detection of weak signal in liquid environment.