Computer color matching is widely applied in industry such as textile printing and dyeing, paint, plastic and building material. The fundamental theory of computer color matching is the linear relationship between Kubelka-Munk function and concentration of dye. But in fact, Kubelka-Munk function is nonlinear with the concentration of dye, which limits the wide appliation of computer color matching in China. Therefore, a kind of mathematical method is put forward and a linear dye database is set up accordingly. Spectrophotometric color matching is an important method for computer color matching. But the change of reflectivity of coordinative spectrum at each wavelength can cause different degree color difference for the object, and the change is sharp at some wavelength while it is lazier at others. So the different degree color difference weight factor at each wavelength is given for spectrophotometric color matching according to colorimetry, and provided with linear dye database. The result show that the linearity of the database is increased obviously and the use of color difference weight factor could improve the spectrophotometric color matching distinctly.