A self-correcting method to calibrate the error of phase shifter is presented. Firstly, the fast Fourier transform (FFT) was used to anlayze the carrier frequency fringes, the characteristic curve of phase shifter was obtained from a series of carrier interferograms by FFT. Using this curve, then the phase shifter was corrected by an iterative self-correcting process relying on the interferometer. The self-correcting experiment with IR interferometer shown that the nonlinearity of phase shifter was reduced from 5% to 0.2%.