All kinds of organisms have their own distribution law of life-related elements, including Chinese medicines, and their oxidation potential is different. Generally,when the oxidation potential is higher,the Yang(+) attribute of ions will be stronger; otherwise,the Yin(-)attribute is stronger. It is discovered in the data from the analysis of the elements of Chinese medicines that the so-called Yin and Yang in the traditional Chinese medicine have close relationship with the distribution of oxidation potential of the elements in the fourth period. In the medicines with Yang attribute, elements with high oxidation potential are superior and on the contrary in the medicines with Yin attribute, elements with low oxidation potential are advantageous. Therefore, oxidation potential can be used to distinguish between Yin and Yang and identify the flavor of Chinese medicines.This paper explores the relationship among the electrophilic intensity of the cations of life -related elements, oxidation potential and the organisms of Chinese medicines,pointing out that linear relationship exists between oxidation potential and charge strength of various cations and that the cation has its Yin and Yang attributes in the light of oxidation potential and different cations have their different offinities for negatively charged electrons in microcircumstance as far as charge strength is concernd. It also indicates the intrinsic reasons of the flavors (pungent,sweet,bitter,acerbity,salty and so on) of Chinese medicines and their corresponding structural characters of organic components and makes a further suggestion that the general organic components and flavors of Chinese medicines could be predicted through the distribution of the elements of biological power.