The invention discloses a frequency domain interpolation electric power harmonic wave analysis method based on discrete Fourier transform. The method comprises the following steps: (1) conducting time domain continuous signal discretization; (2) selecting an appropriate cosine-class window to weight a discrete sampling sequence according to measuring requirements; (3) performing fast Fourier transform on the sequence; (4) finding the two longest spectral lines close to harmonic waves in the form of spectrum peak searching, and calculating a spectrum value ratio between the two lines; (5) obtaining a frequency deviation according to a Newton interpolation method; and (6) further solving the amplitude, frequency and initial phase of sub-harmonic waves on the basis of the obtained frequency deviation. A fast interpolation based on table look-up is independent of a window function. The method is universally applied, and can be combined with any window function to conduct harmonic wave analysis. Meanwhile, no complex operation exits, the computational complexity is low, and the method is easy to realize in an embedded system.