The theoretical system of Neijing has three academic characteristics, namely: the unity of heaven and man, the unity of five internal organs-grasping the law of life as a whole; Life is tangible and cannot be separated from Yin and Yang-dialectical view of life activities; From the beginning of waiting, Tao was born-summarizing the essence of life from the function.

First, the formation conditions of the theoretical system of Neijing

The history of science tells us that the emergence of any theory and the formation of any discipline are inseparable from the historical background of specific social, cultural and scientific development. The formation of the theoretical system of Neijing is also inseparable from the social changes at that time, the infiltration of philosophical thoughts and the influence of natural science and technology. Of course, as a compilation of medical papers, the formation of Neijing was more closely related to the accumulation of medical practical experience at that time.

1. Social changes, witchcraft decline

During the Spring and Autumn Period and the Warring States Period, feudal society replaced slave society. The transformation of production relations has greatly promoted the development of social productive forces and economic prosperity, and economic development will inevitably bring about the development of science and culture. After Qin Shihuang unified China and established a centralized government, it promoted the unification of currency, law and weights and measures.

On the ideological front, by the Warring States period, a situation of "all philosophers are stupid and a hundred schools of thought contend" had been formed, and people explained many phenomena in nature with the help of a simple world outlook. The development of natural science is a record of people's struggle with nature, which shows that people's understanding and control of nature are gradually deepening and improving. Natural science is beneficial for people to get rid of feudal superstition and resist the invasion of theistic thoughts such as witchcraft.

Witchcraft, as a common phenomenon in early human cultural life, penetrated into all aspects of social life. It can be considered that witchcraft is the behavioral response of ancestors to nature and a sign of underdeveloped science. After the Warring States period, the gradual development of materialism and natural science led to the gradual decline of witchcraft. Medical facts educate people,

When people get sick, it is impossible to solve the problem by turning to witchcraft and astrology and begging gods and spirits to relieve the pain of the disease. In this way, the development of medicine has become the need of the times. The authors of Neijing broke through feudal superstition and theocracy, and clearly put forward the view that "those who are confined to ghosts and gods do not even talk about morality". The appearance of Neijing is a sign that doctors and witches parted ways.