Abstract: Backscattering sources and their influence on total backscattering in ring laser gyroscope was analyzed based on vector superposition principle. According to the coupling effect of backscattering on counterclockwise and clockwise beam, the relationship between total backscattering coefficient and light intensity of oppositely directed traveling waves was derived. Based on this relationship, the curve of backscattering was obtained through pushing and pulling mirrors to different places to change the shape of resonator, at the same time, and the amplitude of AC portion was measured. The vector superposition principle of backscattering was verified by comparing it with simulated results.