we know that the parameter vibration signal is usually amplitude, frequency and phase angle. the phase angle has important significance in studying the transmission characteristics of the measured system or the dynamic characteristics of the object in the joint action of multiple vibration sources. Therefore, this paper only discusses the detection of amplitude and frequency and the realization of automatic zero adjustment of detection circuit. according to the characteristics of the low frequency absolute vibration signal, the overall schematic diagram of the detection circuit we use is shown in figure 2.