Abstract: Aiming at the problems of noise interference and mode aliasing in the extraction of sub-synchronous oscillation com-ponents, a method of sub-synchronous oscillation analysis based on high-order Fourier synchrosqueezed transform (HFSST) is proposed. Based on the Fourier synchrosqueezed transform (FSST), a modulation operator is defined to modify the instantaneous frequency estimation through the high-order Taylor expansion of signal amplitude and phase, so as to improve the energy aggregation range and reconstruction accuracy of signal time-frequency distribution. Then, the proposed method is applied to the analysis of sub-synchronous oscillation. The time-frequency analysis and modal decomposition of the sub-synchronous oscillation are performed by using this method, and the oscillation parameters of each component are obtained by combining the method with Hilbert transform (HT). Through the simulation experiment and the analysis of the measured data, the results are compared with those of short-time Fourier transform (STFT), reassignment method (RM), and empirical mode decomposition (EMD). The results show that the proposed method can be adopted to suppress noise interference, obtain better time-frequency distribution of sub-synchronous oscillation, realize mul-ti-component mode decomposition of sub-synchronous oscillation, and accurately identify the parameters of sub-synchronous oscillation, which can provide some references for stable operation of power system.