In this paper, the empirical mode decomposition (EMD) method is introduced and the calculation of the local mean with the envelope method of the extrema is substituted by an improved method, in which the local mean is computed by using the average method of the successive extrema. Based on the improved EMD method, the vibration signals of ball bearings are analyzed in detail. The results show that the proposed method is superior to the discrete wavelet decomposition for the vibration analysis of ball bearings.