A new method combining Empirical Mode Decomposition(EMD) with time-frequency ridge is proposed to estimate the Instantaneous Frequency(IF).In this paper, the EMD method was used to decompose the vibration signal, then the time-frequency spectrum of each Intrinsic Mode Function(IMF) derived based on the EMD was reassigned with the technology of time-frequency reassignment to improve its time-frequency sharpness.Consequently, the ridge of time-frequency reassignment was extracted to obtain the IF estimation.Thus, the shortcoming of noise sensitivity of Hilbert Transform was overcome.The comparison analysis shows that with the ridge extraction of time-frequency reassignment, a precise IF estimation can be gained to realize the order tracking of the run-up signals and the fault diagnosis of hoist gearbox.