According to legend, China's first pharmaceutical work, The Classic of Materia Medica, was written by Shennong. Yan Di Shennong is the ancestor of China pharmacy. He is the first person to study pharmacy with herbs in ancient literature of China. His research achievements in pharmacy and later generations' medication experience were written into China's first pharmaceutical book, Shennong Herbal Classic.

The Classic of Materia Medica was written in Qin and Han Dynasties. This book summarizes the pharmacological achievements of ancient working people in long-term medical practice. The original book has long been lost, and its words have been quoted, and it is still preserved in books such as Zheng Bencao. All kinds of books published after the Ming Dynasty with the title of Shen Nong's Classic of Materia Medica are lost by later generations.

In addition to summarizing the general order of drugs, the book also includes 365 kinds of drugs, which are divided into three categories: upper, middle and lower. Among them, high-grade and middle-grade 120, low-grade 125.