Yin-Yang and Five Elements are the basic philosophical principles of understanding nature, which are gradually summarized from astronomy, meteorology, calendar and other disciplines with the development of ancient natural science in China, through long-term observation and understanding of the movement and changes of nature. Neijing absorbed and developed the main theories of ancient philosophical schools, built its own theoretical system, and formed a unique epistemology and syndrome worship method of using Yang and Five Elements in TCM. Based on "everything originates from qi", it understands and explains everything in the universe by studying the movement and transformation law of qi, and analyzes and demonstrates the physiology, pathology, health preservation, demonstration, treatment principle, treatment method and prescription of human body. Its content is quite rich and runs through all aspects of the theoretical system of traditional Chinese medicine. Most chapters of Neijing use Yin-Yang theory and Five Elements theory to discuss, analyze and summarize the physiological activities and pathological changes of human body, making it an organic part of the theoretical system of traditional Chinese medicine, which has important guiding significance for theoretical research and clinical practice of traditional Chinese medicine.

Yin and Yang are two interrelated and balanced aspects in a specific system.

Yin-yang theory holds that no matter from the point of view of matter, function or the relationship between matter and function, any system has two aspects of mutual care. They make the whole system in a dynamic, balanced and stable state through inductive communication, mutual utilization, growth and decline, transformation and restriction. Due to the different size of the system, the concept of Yin and Yang has different specific connotations and extensions at different levels, so Yin and Yang in traditional Chinese medicine has the characteristics of "there is nothing in it, and there is nothing in it".

Yin-yang theory needs to correctly understand the specific content and application category of Yin-yang theory at different levels. The essence of the five elements, namely wood, fire, earth, gold and water, is a more detailed division of the system. Theoretically speaking, the five elements also have the characteristics of "nothing is big but nothing is small". The theory of five elements mainly discusses the attributes of the five elements in the system and the law that the five elements balance and maintain the dynamic balance and stability of the whole system through restraint and restraint.

Yin and Yang correspond to the orientation of heaven and earth. Fire in the second place, 70% south. There are three trees in the sky, and 80% of the ground is east. Gold is born in four places, and the sky is 90% west. "In the river map: one, three, five, seven and nine (five odd numbers) are days and belong to Yang. Two, four, six, eight and ten (five even numbers) are the ground and belong to yin.

Yin and yang correspond to the human body. "Spring is a livable liver and belongs to wood. Xia Chang is a fire. Autumn harvest is suitable for the lungs and belongs to gold. Winter storage is suitable for kidney, which belongs to water. Spleen is soil. Corresponding to the five internal organs of the human body "

The ideological methods and theoretical viewpoints of Yang Ming's Five Elements Theory run through the chapters of Su Wen and Ling Shu. There are not many chapters devoted to Yang Ming's theory of five elements in Neijing, but the chapters focusing on the concept and application of Yang Ming's theory of golden chamber and strict array in five elements are mainly (Su Wen's theory of anger reaching heaven), Yin and Yang should be like a big picture, and Yin and Yang's theory of separation and engagement? Six hidden images? The theory of dirty qi, Yi Ming's theory of five sounds and five flavors, five qi divided into four hours a day with qi, yin and yang as the sun and the moon, and the theory of nine needles on the pivot.