Abstract: The research results of interferometric all polarization maintaining fiber hydrophone array have been reported. On the basis of detail introduction of structure and performances of all polarization maintaining fiber hydrophone element, the structure and characteristics of four element array have been described. The measurement results of frequency responses of array element relative receiving sensitivity and array directional responses have been given. At the meantime, the differences in performances, signal transmission and processing and other aspects between optic fiber hydrophone and traditional piezoelectric transducer have been given.