The fault diagnosis of rolling bearing plays a significant role in rotating machinery. This paper makes a comparison between the acoustic emission and vibration signal in the fault diagnosis of the bearing of outer race pitting. The acoustic emission and vibration signal are processed by the wavelet transform, Hilbert envelope transform and FFT transform. Finally, the spectrum charts of the signals of acoustic emission and vibration are drew out. Based on the analysis results, the conclusion can be drawn that acoustic emission is superior to vibration in the fault diagnosis of the bearing.