To propose an idea of quality identification of individual Chinese medicinal and the concept of quality identification of traditional Chinese medicinal population, and to establish a system of theoretical distinguishing approach for population traditional Chinese medicinals with identical quality. Methods:According to dual index information theory equation I=-(PglnPg+PalnPva, which can describe the biological inheritance and variation information, an absolutely and accurately quantitative standard Pg≥61% was deduced. It was qualified to be the theoretical criterion for individual traditional Chinese medicinal with identical quality. Relying on the standard, each sample’s characteristic sequence could be set up. Moreover, in reference to the randomness, the fluctuation and the asymmetry of biological properties, the optimum distinguish method for traditional Chinese medicine population with identical quality was built up too, which was named the maximum efficient sample number method of population characteristic sequences. In this method, to vary the x ≦Pg ≦100%， 58%≦x ≦64%, and to optimize all samples’ characteristic sequence in order to make the difference of total sample number, involved in the core characteristic sequences of all samples, between the total sample number, in relative sequences of all samples, that is Y =(Nci-Nri ), to be the largest. In this way the quality of traditional Chinese medicine was discriminated optimally. This systematical theory is able to perform strict theoretical identification of traditional Chinese medicine population with identical quality as well as individual medicinal quality. Results:This approach, or theoretical prediction was perfectly proved by the analysis of infrared fingerprint spectra of three species of traditional Chinese medicinals with very similar composition. Conclusion:This research provides us with a qualified theoretical method for recognizing identical Chinese medicinals quality.