The backscattering noise of the resonant loop is one of the main optical noises in the resonator fiber optic gyroscope (RFOG) system.Based on the theoretical analysis of the influence of the backscattering noise in the resonant ring on gyro output error,comparing the influence of different modulation waveforms and carrier suppression channels,the best solution is the triangular modulation with dual-channel.Based on this scheme,a theoretical model of the relationshi p between the gyro bias and bias stability (BS) error with the modulation voltage amplitude and noise is established. Combining the gyro parameters with a diameter of 0.1 m,total fiber length of 10 m and the fineness of 24,the requirements of the gyro zero-BS caused by backscattering n oise on modulation voltage variation range and quantitative index of noise amplitude is obtained.I t lays the foundation of error distribution and control parameter design for specific precision gyro.