This paper presents a real-time fault diagnosis method of rolling bearing based on cross-correlation detection, which is easy to be realized by analog circuits. The method uses two acceleration sensors to collect the bearing vibration signals from different points, and sends them into the high Q band pass filter to select the optimum resonance band. Then, it sends the output signal of two band pass filter to cross-correlation detection. After that,the result of cross-correlation detection is filtered by low pass filter, which can keep the low frequency fault signal. Finally, the output signal of low pass filter displayed the fault characteristic frequency of rolling bearing by spectrum analyzer. So far the real-time fault diagnosis of rolling bearing is realized. In this paper, the proposed method is built in the form of analog circuits, and the real-time fault diagnosis of rolling bearing is completed on the QPZZ-II platform, it shows that the method not only overcomes the limitations of a single source, using cross-correlation function weaken resonance with internal noise,so as to make the diagnosis with higher spectral identification rate, but also the method of analog circuit has the advantages of simple structure, easy maintenance, the real-time fault diagnosis of bearing fault method applications and popularity have a certain reference value.