In order to describe physiological and pathological changes of the tongue more objectively,a method based on spectrum was investigated.According to lighting standard and observation condition recommended by International Commission on Illumination(CIE),reflectance spectrum was measured and normalized to eliminate the effect brought by measure condition.By picking up the signals at different wavelengths,the color of the tongue can be showed exactly.Many parameters related to human’s health,such as microstructure,composition and microcirculation of the tongue,can be acquired too.More effective and accurate information can be brought forward than the traditional methods.Preliminary experiment showed that it can not only reflect small differences of the tongue,but also can describe physiological and pathological changes.By reflecting the information with characteristic parameters,this method was combined with physical reference to promote the research process of TCM.