The source and characteristic of fiber-optic gyroscope（FOG） random noise is analyzed in theory.Two methods of analyzing the FOG random noise

Allan cvariance method and model fitting method using in the military standard of PRC

are introduced.And then the static data is used to calculate the noise contents in FOG’s output by using these two methods.The result shows that the output signal contents quantization noise

angle random walk noise anglt

rate random walk noise

bias instability and rate ramp noise

among which the last three noises are more important.The mothod is very useful to research FOG.