The visible spectrum fingerprints of infusion color of seven grades of Xinyang Maojian tea were established by using the colorimeter to scan the tea infusion continuously under the wavelength of 400-700nm. Based on the ratio of reflectance and transmittance under each wavelength, the method of discriminant analysis was used to differentiate grades of Xinyang Maojiao tea with the accuracy more than 90%. Seven methods were used for fingerprint similarity calculation which all can reflect the difference between grades of the tea to different extent, while the new improved extent similarity method was proved to be the best. The results of similarity calculation in grading of teas were consistent with that of discriminant analysis and the difference between grades can be quantified. This provides another objective and quantitative method for quality evaluation and quality control of green tea.