For the evaluation of cathode-ray tube (CRT)perceptible color difference threshold characteristics of the visual color matching, the experiment is carried out. By using the compiled color-matching program, the CRT generates color under gray background randomly. The matching color and the random color can achieve visual color matching by adjusting the R, G and B channels in the program, then the values of L*, a* and b* of the matching color and the random color are measured respectively. Upon the data processing and analysis of the experimental results, in terms of lightness, chroma and hue,the color difference formula CIEDE2000 is superior to CMC (2:1) and CIE L*a*b* in different aspects. Then experimental color discrimination are plotted in a*b* diagram. Furthermore, different color difference formulae have different thresholds for evaluating CRT perceptible color difference threshold.