Gyro’s drift is not only the main drift error which influences gyro’s precision but also the primary factor that affects gyro’s reliability.Reducing zero drift and random drift is a key problem to the output of a gyro signal.A three-layer de-nosing threshold algorithm is proposed based on the wavelet decomposition to dispose the signal which is collected from a running fiber optic gyro(FOG).The coefficients are obtained from the three-layer wavelet packet decomposition.By setting the high frequency part which is greater than wavelet packet threshold as zero,then reconstructing the nodes which have been filtered out noise and interruption,the soft threshold function is constructed by the coefficients of the third nodes.Compared wavelet packet de-noise with forced de-noising method, the proposed method is more effective.Simulation results show that the random drift compensation is enhanced by 13.1%,and reduces zero drift by 0.052 6°/h. Gyro’s drift is not only the main drift error which influences gyro’s precision but also the primary factor that affects gyro’s reliability. Redcing zero drift and random drift is a key problem to the output of a gyro signal. A three-layer de-nosing threshold algorithm is proposed based on the wavelet decomposition to dispose the signal which is collected from a running fiber optic gyro (FOG). The coefficients are obtained from the three-layer wavelet packet decomposition. By setting the high frequency part which is greater than wavelet packet threshold as zero, then reconstructing the nodes which have been filtered out noise and interruption, the soft threshold function is constructed by the coefficients of the third nodes. Compounded wavelet packet de-noise with forced de-noising method, the proposed method is more effective. Simulation results show that the random drift compensation is enhanced by 13.1%, and reduces zero drift by 0.052 6 ° / h.