A kind of single beam Ultraviolet and Vacuum Ultraviolet(UV-VUV) spectrophotometer is designed based on the principle of spectrophotometer.It primarily consists of a 150 W deuterium lamp,a toroidal mirror,a Seya-Namioka holographic concave grating monochromator,a collimator,samples/detector rotators,a photomultiplier tube and a system controlled by computer.The optical system of the spectrophotometer is optimized using ZEMAX optical design software,and a sine bar mechanism for wavelength scanning is designed.The analyzed results show that it satisfies the design requirements of the spectrophotometer.Spectral region from 115 nm to 400 nm can be scanned,and its spectral resolution is less than 0.5 nm with wavelength accuracy less than 0.1 nm.