The theory of traditional Chinese medicine began in the Inner Canon of Huangdi.Its discussion of ascending and descending theory of qi mechanism mainly includes:ascending and descending in the movement of heaven and earth,ascending and descending in the human body,and ascending and descending in all things in nature.The description of the ascending and descending theory of the qi mechanism focuses on nature and the human body and slightly discusses drugs.ZHANG Yuansu of the Yishui school,based on the ascending and descending theory of the qi mechanism in the Inner Canon of Huangdi,created the theory system of medicinal properties including ascending,descending,floating,and sinking.ZHANG Yuansu was influenced by the principle of “correspondence between man and universe” and placed medicine in the context of heaven,earth,and the four seasons.Based on the characteristics of qi movement in the four seasons,it was proposed that drugs have a tendency to ascend,descend,float,and sink.By corresponding the nature and taste of medicines to the yin and yang of heaven and earth,the theory of ascending,descending,floating,and sinking of medicines was discussed according to the theory of “qi interchange”.According to the “tonification and purgation of five organs”,on the basis of tonification and purgation by medicinal taste,tonification and purgation by medicinal qi was supplemented.The general trend of ascending,descending,floating,and sinking of drugs was established through qi and taste,so as to regulate the qi of the internal organs.The theory of ascending,descending,floating,and sinking of medicinal properties proposed by ZHANG Yuansu enriches the content of the Inner Canon of Huangdi on the ascending and descending of the qi mechanism of drugs and lays the foundation for the development of the theory of medicinal properties in the future.