Because paper with fluorescent additives will absorb ultraviolet light while excite visible blue ray or violet fluorescence, these will certainly affect the blue or violet ink thickness. The traditional methods do not accurately reflect ink thickness changes. Based on the Fluorescent Clapper-Yule spectral reflectance prediction model, considering the expansion of ink, optical properties of paper with fluorescent additives, the internal lateral spread of light in paper with fluorescent additives and other features, an ink thickness variation prediction model was established using least square method and by spectrum reflectance of prints. The model can make a coloring analysis for color prints and provide a theoretical basis for print quality inspection systems development.