Abstract: A nonlinear and non-stationary signal processing method is proposed for the identification of low frequency oscillation in power system which is called Hilbert-Huang transform (HHT). In this paper, we first pretreat the noise and delay compensation of the oscillation signal, and then identify the modal parameters with the In this paper, we first pretreat the noise and delay compensation of the oscillation signal, and then identify the modal parameters with the HHT. Finally, the improved Prony algorithm identification results are compared with HHT. The simulation results show that the empirical mode decomposition can filter out the noise interference in the signal and lay the foundation for the accurate analysis of modal parameters. Moreover, the HHT method can effectively decompose the oscillating modes, and then accurately identify the modal parameters and obtain the time-frequency characteristics of the oscillation modes.