To study the mechanism and characteristics of friction vibration,mixed/fluid lubrication experiments were designed based on Stibeck curves,and the vibration signals under different conditions were analyzed in statistical time domain.The results show that under the condition of fluid lubrication,the frictional vibration is very weak,the root mean square (RMS) of vibration signal does not increase with the increase of load,the autocorrelation function of tangential vibration signal changes smoothly,and the crosscorrelation function of normal and tangent vibration signals is relatively smooth.Under the condition of mixed lubrication,the RMS of vibration signal is increased with the increase of load.Both the tangential vibration signal autocorrelation function and the twodirection vibration signal crosscorrelation function have obvious impact characteristics.Statistical characteristics of vibration signals measured by comparative analysis can identify two lubrication states.