The accuracy of colorimetric characterization using the look-up table (LUT) method and effect of the black point were studied, and experiments were performed on a colorful CRT monitors of SONY G520. The experimental accuracy of characterization is presented as three kinds of color difference units of CIELAB, CIE94 and CIEDE2000: (1)0.84, 0.40 and 0.42 at considering the black point, and 1.87, 0.74 and 0.76 at not considering one in the characterization equation when the intensity of the black point is larger (i.e. CIE XYZ=1.31/1.19/0.97 in experiments); (2) 0.87, 0.41 and 0.38 at considering the black point, and 1.06, 0.47 and 0.44 at not considering one when the intensity of the black point is smaller(CIE XYZ=0.08/0.10/0.12). This result denotes that whether the effect of the black point should be considered in the characterization equation is related to the intensity of the black point. When the intensity is stronger (weaker) its effect on the accuracy of colorimetric characterization is larger (smaller).