The theory of Rayleigh backscattering noise in the silicon substrate micro-optical resonance gyro (MORG) is described, and the static-and dynamic-state models of MORG are constructed. Characteristics of this noise in the resonator of SiO2 on Si substrate are formulized. The relationship between the Rayleigh backscattering noise and main signal intensity, and the effect on the main signal by the interference signal of the noise and reverse optical signal, are simulated by software algorithm. Effect of this noise on the performance of the resonator,such as the definition and the maximal sensitivity, is analyzed. The scheme to suppress the noise is proposed. Based on the anslysis, the experimental system is set up. The results agree well with theoretic calculation.