Abstract: In order to solve the problems (slow rate and big volume) which the existing color measuring instruments are confronted with, a mathematical model for color measurement was established with the advanced optoelectronic spectrograph method for color measurement and an automatical spectrophotometer was designed. The system consists of illumination system, optoelectronic spectrograph, signal collecting and processing circuit, and color measuring software. The design of the illumination system and optoelectronic spectrograph are introduced in detail. Photoelectrical spectrograph device uses a flatfield concave grating as a beamsplitting device and the linear array CCD as detectors, thus, the volume of instrument was reduced. Seven standard color boards were measured with the spectrophotometer, and the result is that the measurement uncertainty of chromaticity coordinate is less than 0.01 and color measurement period is 1 s. These indicate that the instrument can meet the requirements of rate and accuracy in color measurement in industry.