The acoustic sensing characteristics of an active optic fiber hydrophone was analyzed. The fiber laser sensor is made by writing Bragg grating with πphase-shift into a section of Er-doped fiber. Acoustic pressure applied to the fiber laser induces laser wavelength shift. The wavelength shift is demodulated through interferometric interrogation scheme, and the acoustic pressure information is obtained. The sensitivity experiment shows that the sensitivity is -1665 dB(reference value, 1 rad/μPa). Four optic fiber hydrophones were spliced along a single fiber to form an array. A band-pass wavelength division multiplexer was used to separate the composite interferometer signal into discrete channels and demodulate the acoustic pressure information. The experiment shows that the crosstalk of the array is less than -60 dB, and it will not affectthe dynamic response range of a single hydrophone.