“The unity of nature and human” is the cognitive method and idea of ancient Chinese sages to explore the relationship between human and nature. It originates from in three emperors’ period and arises from the plain perception of nature. Through the Zhou Dynasty, the concept of “destiny” and “Son of Heaven” was established. From the Spring and Autumn and Warring States period to the Qin and Han dynasties, the perception of the relationship between nature and man underwent a transformation. And then the Jin and Tang periods continued to explore. The turbulent changes from the Five Dynasties and Ten Kingdoms to the Two Song Dynasties. During the Ming and Qing dynasties, the philosophers pondered and changed. “Nature and Humanity” cognition has experienced a long history of change and formed a unique theory and practice system. This paper explores the core content, characteristics and evolution rules of the cognition of “the unity of nature and man” by sorting out the changes in the cognition during the historical development.