Up to now, almost all conventional cathode ray tube (CRT) colorimetric prediction models are based on the “superposition principle of tristimulus values”. Through a series of experiments. It is found that there exists a kind of “suppressive effect” among RGB channels in practical CRTs, and this effect will invalidate the superposition principle and result in the interactive errors in conventional CRT colorimetric prediction models. The experimetal results show the errors caused by this “interaction effect” will increase with the luminance values on the CRT screen.