We introduce the fundamental of the phase operating point stabilization of Fabry-Pérot interference optical fiber hydrophone based on the loop-locked feedback control method, present the sound pressure phase-shift sensitivity expression of the Fabry-Pérot optical fiber hydrophone and deduce the Fourier transformation formula of transmission intensity substitution function of Fabry-Pérot interferometer. By MathCAD, we draw the Fourier transformation spectra of the above formula. Following the spectra, we can directly understand the composition and the characteristic of the system output signal. In experiments, the Fourier transformation spectral from transmission intensity of Fabry-Pérot optical fiber hydrophone is recorded by a spectral analysis instrument, which tallies well with the spectral drawn by MathCAD. Through the experiment, we further point out the choice method of the critical feedback point frequency, and examine the actual effect of the feedback control method in the stabilization of phase operating point process of Fabry-Pérot interference optical fiber hydrophone. The validity of the method is proved.