Fast axis ajustable photoelastic modulator (FaaPEM) not only has the advantages of high modulation frequency, large aperture, and good seismic performance, but also makes up for the shortcomings of traditional elastic optical modulator, such as phase delay and fast axis azimuth. It plays an important role in polarization modulation and polarization measurement. FaaPEM is a resonant optomechanical device composed of two piezoelectric drivers and elastic optical crystals. In the high voltage resonant state, due to its own temperature rise, the resonant frequency of elastic optical crystals does not match the frequency of driving voltage, which greatly affects the modulation efficiency of incident light. In order to ensure the optimal modulation capability and stability of FaaPEM at work, this paper carries out the research on the stable closed-loop control of FaaPEM, proposes a closed-loop drive control method based on modulation signal tracking and phase regulation, and tests the stability of FaaPEM. The test results show that the stability of the system reaches 4.18% under half wave state and 3.43% under quarter wave state after loading feedback control.