Traditional integral colorimeters use tungsten–halogen or xenon lamps for illumination, as well as correcting filters to make the instrument's spectral response meet the Luther condition. This structure causes the instruments to have relatively higher error and poor repeatability. Thus, this letter proposes a new measurement design that uses compound LEDs as the instrument's measurement light source. The new design adjusts the instrument's spectral response by modifying the spectra of the compound LEDs. A compound LED light source is designed for integral colorimeters, and an experiment is conducted to evaluate the performance of the integral colorimeter. Experiments show that the design effectively reduces the error of integral colorimeters.