Disclosed is a sub-synchronous oscillation parameter identification method for synchronous phasor data based on interpolation DFT. The method comprises the following steps of 1, acquiring real-time high-resolution waveform data; 2, obtaining a synchronous phasor Xr(m) at a master station; 3, conducting a discrete Fourier transform operation on the synchronous phasor Xr(m) in a rectangular window to obtain a discrete Fourier transform spectrum Fr(k); 4, determining a frequency spectrum line km with the largest sub-synchronous oscillation amplitude; 5, constructing index phasors [k1, k2, k3, k4], introducing a frequency spectrum Frs(ki) of a second-order difference optical spectrum, and obtaining a simplified second-order difference ratio R; 6, calculating the values of a frequency fs and adamping coefficient alphas of sub-synchronous oscillation components; 7, conducting Hann window interception on the synchronous phasor Xr(m), executing the discrete Fourier transform operation, and conducting backstepping to obtain a calculation formula of the amplitude value As of the sub-synchronous oscillation components. By means of the method, the parameters of the sub-synchronous oscillationcomponents can be accurately identified, and the alleviation of the influence of sub-synchronous oscillation on system stability and equipment safety is facilitated.