When the multi-spectral sensor works in the space, it is affected by temperature variations, space radiation and other factors, which may produce changes in the spectral response characteristics. As a result, bias occurs in the physical measurements which cannot be corrected by radiometric calibration methods. With the help of spectral targets and appropriate degradation models, the degradation characteristics of the multi-spectral sensor can be assessed. To achieve this purpose, suitable spectral targets should be designed. Based on simulation experiments, it can be concluded that the targets with Gauss model spectral reflectance are the most suitable for on-orbit assessment, and the on-orbit experiment result verifies the conclusion above.