Abstract: Aiming at the problem of noise jamming in the vibration signal of roller acquisition process of the control rod drive mechanism (CRDM), a de-noising method combining semi-soft wavelet threshold and Hilbert transformation was proposed. First, the semi-soft wavelet threshold was used to denoise the vibration signal of roller in the time-frequency domain, then the Hilbert transformation was used to find envelope spectrum, and the different vibration signals of the roller in the life test and the defect verification test were analyzed. The result shows that this method can effectively eliminate the noise jamming on the vibration signal, which proves the validity of the method in the state recognition and fault diagnosis of the CRDM, and provides theoretical support for the state recognition of the CRDM.