The dispersion principle of common used monochromators is described. The optical constructs of several kinds of reflective and horizontal imaging systems are introduced and their wavelength calibration and energy calibration methods are given. The application status of current remote sensing instruments boarding on different monochromators is illustrated, such as the applications of the Moderate Resolution Imaging Spectroradiometer (MODIS), Solar Spectrometer (SOLSPEC), Solar Backscatter Ultraviolet Spectrometer (SBUV), Ultrariolet Ozone Vertical Profile Probe (UOVPP-SBUS) and TRUTHS task from European Space Agency (ESA) to radiation measurement, spectral calibration and absolute calibration. Finally, it discusses the possible developing trends and application prospects of space monochromators and points out that the absolute calibration system by taking the sun as the light source and combining a space monochromator with a cryogenic absolute radiometer is one of the most promising trends in the future. , 2015, Chinese Academy of Sciences. All right reserved.