A spectral correction method was proposed for an infrared space-borne Fourier transform spectrometer by using Instrument Line Shape(ILS). The ILS of the Fourier transform spectrometer was introduced systematically. An ILS model was established based on the instrument characteristics, and the simulation and calculation were carried out by using the MATLAB. The laser spectral peak value difference between the center detector and the edge one was calculated in theory, and the relative error between theoretical calculation value and actual value is just 4.21% and the accuracy of the corrected spectrum by the edge detector reaches 10-5 magnitude. The results verify the validity of the spectrum correction of the plane array Fourier transform spectrometer by using ILS in the theory. Finally, a method was proposed to correct the non-central pixels' spectrum of the plane array Fourier transform spectrometer for engineer applications. The experiments show that the method has stronger universality and both guarantees high spectrum accuracy and improves the efficiency of spectral calibration. Moreover it reduces the workload of spectral calibration.