Aesthetics is a discipline that summarizes the characteristics and laws of human aesthetic practice experience. It is a subject that studies beauty, artistic aesthetics, aesthetic consciousness, and the aesthetic relationship between man and reality, but these viewpoints have defects and deficiencies. An important basic category in aesthetics is the essence of beauty. What is the essence of beauty? There are many opinions. The first view holds that beauty is an objective concept or absolute spirit. The second view is that beauty is endowed by people's urban aesthetic feeling (feelings and tastes) in aesthetic activities, which is subjective; People think that things are beautiful and seek for things to be beautiful. The third view is that beauty is "order and symmetry" in the form of objective things. The fourth view holds that beauty is the attribute that objective things can make people happy. The fifth view holds that beauty is an attribute influenced by social relations with people. The sixth view holds that beauty is a kind of life that can be seen in things and should be so according to our understanding. It is a kind of loved, precious, vivid and diverse life. The seventh view holds that beauty is the essential strength of human beings and the humanized content embodied in the environment created by human beings in social labor practice. It should be said that the essence of beauty should be able to summarize the form and content of beauty. Natural beauty and social beauty created by human beings without transformation should be expressions suitable for multiple changes, and there should be objective standards that can be established in many different and contradictory aesthetic viewpoints. This definition is not only broad and comprehensive, covering all forms, levels and changes of beauty, but also can be used to explain all kinds of concrete beauty. In this direction, as long as we continue to explore, advance one after another and pass it on from generation to generation, we will always get closer and closer to the theory of surplus.