The constants of 2 traditional Chinese medicine (TCM) herbs in the complex biological system were analyzed based on the maximum information states of Dual index information theory equation and common heredity and variation information theory.The common peak ratios of the 2 species constants were Pg=61% and Pg=70%，which respectively corresponding to symmetry and asymmetry variation states，were used as 2 absolute quantitative criteria to identify complex biology systems-TCM.Considered the influences of many other factors on components and experiment processes，the really theoretical identification standards should be established Pg≧(61±3)% and Pg≧(70±3)%，within the relative error±3% of information value around the maximum information states.Methods:The infrared (IR) fingerprint spectra (FPS) of their powder in 4 out of 42 compounds including Guifu Dihuang Pills，Jinkui Shenqi Pills，Mingmu Dihuang Pills，Zhibai Dihuang Pills were tested and analyzed.A total of 6 pairs of 4 different compounds were tested.Results:The result showed that 5 compounds followed the species constant Pg=61%，and 1 of them，the pair of Guifu Dihuang Pills and Zhibai Dihuang Pills，obeyed the species constant Pg=70%.The correct identification ratio of samples was 95.2%，and that of species was 100%.Conclusion:The 2 species constants provide the scientifically and absolutely quantitative standards for identifying and classifying traditional Chinese medicines.