The acoustic emission signal has high frequency and wide bandwidth, and it composes a variety of frequency components. Aimed at the problem of multi-band resonance demodulation of the rolling bearing fault acoustic emission signal, the filter bandwidth is determined usingprior knowledge of the bearing fault frequency, and the frequency of the multi-band resonance demodulation is determined through the iterative search of the Protrugram algorithm. The simulation and test results show that the narrowband envelop demodulation method can recognize several effective demodulation narrowbands, and the corresponding envelop spectrum of each narrowband succeeds in identifying the fault frequency. The fault frequency spectrum is obvious, and the harmonic components dampen substantially.