Time-grating sensors often exhibit non-simultaneous sampling and non-integer sampling during signal sampling. There is spectrum leakage and fence effect when traditional fast Fourier transform（ FFT） is used to analyze harmonic error. Aiming at this problem

an harmonic error analysis algorithm based on Nuttall window and triple-spectrum interpolation FFT is proposed

which uses the Nuttall window function as the harmonic analysis method of FFT to reduce the error caused by the spectrum leakage. Meanwhile

triple-spectrum-line interpolation is applied for modifying the error to reduce the error caused by the fence effect. By MATLAB simulation and experiments

the results show the algorithm can further improve the accuracy of harmonic error analysis from 0. 1 "to 0. 06" by utilizing the windowing function. Experimental study of the error curve of time-grating sensor further validates the effectiveness of the algorithm.