This paper presents a method to diagnose the complex fault of the roto r imbalance and slight damage of the roller bearing. The second generation wavel et and the extremism field mean mode decomposition (EMMD) were employed to separ ate the coupling features of the complex fault and to extract the frequency of f ault signals. Firstly, the original signals were decomposed and reconstructed by usi ng the second generation wavelet. Then, the nonmodulation lowfrequency fault featu re was extracted by applying FFT to the lowfrequency signals from the decompos i tion and reconstruction of original signals. Lastly, the highfrequency modulat e d signals from the decomposition and reconstruction of original were analyzed by envelop demodulation using EMMD, by which the modulated fault feature was extra cted. The results of engineering signals indicate that the method can extract th e complex fault feature of the rotor system.