The invention discloses an interharmonic component restoration method based on phasor measurement data, which comprises steps: spectrum analysis is carried out on a complex phasor sequence of phasor measurement data acquired by a PMU (Phasor Measurement Unit), and a sub synchronous harmonic frequency and a super synchronous harmonic frequency are obtained; according to the sub synchronous harmonic frequency and the super synchronous harmonic frequency, in combination of a real part sequence and an imaginary part sequence of the phasor measurement data, multivariate linear equations are built, and according to the built multivariate linear equations, the amplitude of the interharmonic component of the phasor measurement data is solved and determined. According to the embodiment of the invention, the sub/super synchronous harmonic component in the system can be decomposed accurately, the frequency and the amplitude of the interharmonic can be accurately calculated, effective monitoring on the interharmonic existing in a power system can be realized, and based on a corresponding monitoring result, the stability of the power system can be improved.