Accurate grading is necessary to ensure the quality of tiles. The quantity of color difference is an important base for grading tiles. For this reason it is necessary to quantify the color differences of tiles. This paper presents a new method of using computer vision technology to measure color differences tiles. It uses CCD image sensors to obtain color images of tiles. The images are then processed with computer to produce the RGB of the color image. The image is then converted from RGB space to CIE1976L*a*b* color space. The character colors are then obtained. The color differences is then determined based on the character colors. A measure system and the color difference computing software were designed. Results from experiments were also given in this paper that color difference values with the different color index are larger than the same color index. The experimental results show that this measuring method can be used for real-time measuring for ceramic tiles.