The color assessment cabinet has an important application in the fields of color printing, photography, dyeing and intelligent instruments. Krypton gas lamp is used as the A light source. By choosing 29 kinds of COB integrated packaging and high-power LED chips as the basic luminous unit the spectrum of B, C and D65 is simulated. Based on the measured linear normalized spectral power distribution data of each LED spectral model, a spectral matching algorithm based on genetic algorithm is proposed, and the proportion coefficient of each LED optical power is calculated through this algorithm. Based on the cold white LED optical power, the LED drive current control parameters are obtained from the linear fitting equation of the optical power and the driving current of each LED. The relative spectral difference of B, C and D65 spectra obtained from this method is 9.1%, 7.98% and 8.05%, respectively. The color rendering index of each fitting light source is 95.5234, 96.6841 and 99.2833, respectively. The color rendering index of the A light source obtained by krypton gas lamp is 99.3330. This design method can meet the requirements of the index very well.