To measure the spectral sensitivity of the photosensitive material, an exposure system for the spectral sensitivity detection of the photosensitive material is designed by use of commercial software of Code V and SolidWorks. The structural differences of the optical path are analyzed using line density of grating under diverse incident angle. The analysis result is that the incident angle of 25° and line density of 350 L/mm are optimum parameters of the exposure system. The experimental result in the system shows that the rectangular spectra of the size of 201.5 mm×80 mm can be achieved, the wavelengths cover the range of 360 nm~900 nm, the intensity of spectra can be adjusted in the range of 0.52 mW?10.65 mW when an 18 gray scale level of slices are inserted in the exposure system, and the resolution of spectra is 0.021 nm, which satisfies the requirement of the exposure system.