The law of color mixing and addition is the basis of all color matching, and the objects’ colordifference generated by different light sources plays an important role in light source colorimetry.We used athree-color laser to produce a white color beam with the same energy ,and found that the mixed color variedwith the luminous flux of any of the lasers, which verified the Galassmann's color mixing law.At the sameime ,an experiment was designed to show the changes of the three slimuli and chromaticity coordinates of thesame object under the changes of the illumination of different light sources, which verified the relationshipbetween the object color and the light source color