A laser reference interferometer to eliminate the distortion of recovery spectrum caused by piezoelectric ceramic’s non-linear modulation in fiber Fourier transform spectrometer (FFTS) was desingned. It can offer equal sampling intervals for sampling tested source, and the basis calibration for the tested spectrum. The interference signal of 632.8 nm He-Ne laser is acquired by the fiber Michelson interfermeter (FMI). Fourier transform algorithm is used to calculate the spectrum. The difference between the spectrum acquired by the experiment and traditional grating spectrometer which can present helpful reference to develop FFTS further was also analyzed.