Abstract：Man, existing as an individual, is produced by practice (especially by material production) gradually. During the process of practice's developing into creation, man attains different levels of freedom. It is man's freedom of practice creation that humanlize nature and man himself, and produces aesthetic relationship between man and reality, which embodies as beauty in the object, as the sense of beauty in the subject. Man's freedom of practice creation is a synchronic structure as well as a diachronic process. So it has different levels of freedom and can be divided into: freedom, quasi freedom, unfreedom, anti freedom. Based on the different levels of freedom, aesthetic categories such as beauty, ugliness, grace, muscular beauty, tragic, comic, humour, ironic, etc. come into being. These categories can be transferred into one another, thus form a complicated system of aesthetic categories.
