The Fourier Transform Infrared (FTIR)Spectrometer has the advantages of high flux and high signal-to-noise ratio.With the help of step scan and the time resolution functions of the spectrometer,FTIR system can be applied to characterize the photo-response spectrum of the infrared focal plane arrays.The response spectra of all the pixels can be measured at once.In the whole spectrum range of 400~10000 cm-1,the spectral resolution can reach 4cm-1.