Abstract: Optics is the key part of a spectrophotometer, which directly affects system performance and accuracy. With portable, low cost, appropiate spectral range and resolution requirements as design target, the crossed Czerny-Turner structure based on plane diffraction gratings was proposed based on the operation principle of spectrophotometer and the theory of optical design. Comparison of some feasible design solutions were made, which included Littrow system, ebert-Fastie system, Czerny-Turner system and crossed Czerny-Turner system. Optical software was used for simulation and optimization of optics. The system spectral range is 360nm-740nm, spectral resolution is 10nm, F number is 5.25, spectrum width is 44.4nm, and the volume of the optical system is 80mm69mm62mm, which meets the design requirements.