The resonant optical gyro system requires the laser tracking to lock the resonant frequency for angular velocity detection, but there exists the optical power fluctuation problem in the semiconductor laser used in it. Affected by the residual intensity modulation of phase modulator, the center of demodulation curve of the system will be offset, resulting in lockin deviation of the gyroscope system and longterm drift of the output path. In this regard, the simulation and experimental test are carried out in this paper. And by calibrating the optical power and the center point of the demodulation curve, the linear relationship between the two is obtained, and the gyro output error caused by the optical power fluctuation can be eliminated through realtime detection of the lock frequency point of the optical power compensation gyro system. In this scheme, the bias stability of the gyroscope system is tested to be 80 (°)/h, and the output path has no drift, which can improve the longterm working stability of the gyro system.