Xiyuan Hospital of China Academy for TCM, cooperated with other units, on the basis of making use of computer image technology and combining TCM theory of tongue inspection, developed the expert system of tongue inspection of TCM and accomplished the quantitative analysis of tongue inspection. The system was used in quantification study on the tongue body and tongue coating for 927 patients. The results showed that each kind of tongue body and tongue coating had its corresponding quantitative RGB (three basic color, R is redness, G is greenness, B is blueness) characteristic. RGB value of tongue coating is related not only to the color, but also the thickness, curdy appearance, greasinessl of tongue fur and so on significantly. RGB value between different tongue fur is different significantly. The percentage of tongue coating area can basically reflect the tongue coating covering area. Therefore, the application of tongue inspection of TCM on the quantificational diagnosis of the tongue body and tongue coating can provide objective references for clinic of TCM.