Gyroscope random drift may influence the precision of the inertial navigation and GPS/INS integrated navigation.In order to effectively identify the parameters of random drifts of fiber optic gyro（FOG）

the autocorrelation function

power spectral density（PSD） and Allan variance are introduced to analyze the raw FOG data.The result shows that the angle random walking noise can be identified by all the three methods

and the angle rate random walking can only be recognized using Allan variance.The angle random walking parameter of PSD is 0.068 8°/h1/2

and the same one of Allan variance is 0.044 7°/h1/2.The result of PSD and Allan variance are similar to the parameters of specifications.The Allan variance could be used as reference for the FOG random drifts.