As the mutation signals hidden in the vibration data of engine's high-speed bearing are difficult to pin- point in time domain,a new algorithm to obtain the amplitude-time inflection point of mutation signals is proposed.Firstly,the characteristic frequency of the signal is extracted via discrete Fourier transform.Secondly,a time-lapse Fourier analysis of the frequency is executed,which helps obtain amplitude-time inflection points.Then,the ap- pearing and disappearing moments of the mutation signal are discovered according to the inflection points.Finally,the amplitude of the mutation signal is obtained via the quadratic Fourier analysis of the signal in a certain period.The results of theoretical analysis,theoretical simulation and engineering simulation all indicate that the proposed algorithm can capture the amplitude of mutation signals accurately,and obtain the appearing and disappearing mo- ments of mutation signals in vibration data.