Interfacial speeds of air and oil of annular flow in straight pipe of oilair lubrication system were defined,transient time values of oil film thickness under different air and oil interfacial speed were calculated by simulation,the autocorrelation function,crosscorrelation function and power spectral density of disturbance wave of oil film were studied by timefrequency method,the disturbance wave characteristics of airoil annular flow in oilair lubrication system were analyzed.The results show that the characteristics of autocorrelation function,crosscorrelation function and power spectral density function of disturbance wave signal of oil film under different interfacial speed of air and oil are different.At constant interfacial speed of oil,with the increasing of interfacial speed of air,the average wave speed and wave length of disturbance wave are increased and the mean frequency is decreased,the energy carried by the disturbance wave in the annular flow film in the low frequency region is reduced.At constant interfacial speed of air,with the increasing of interfacial speed of oil,the average wave speed,wave length and mean frequency of the disturbance wave are all decreased,the energy carried by the disturbance wave is mainly in the low frequency region,and the energy fluctuation is remarkable in the low frequency region.