In the study of the fault diagnosis method of star-rated gearbox, the high-speed shaft is often used to detect the fault information of the medium speed shaft. The frequency component of the medium speed shaft is susceptible to the interference of the high-speed shaft, resulting in the low signal-to-noise ratio. By combining the variational mode extraction algorithm and the maximum correlation cliff deconvolution algorithm, the correlation frequency component of the medium speed axis can be effectively extracted while suppressing the noise component in the original signal, so as to solve the problem that the correlation frequency of the high-speed axis under the measurement point is vulnerable to other signals.