Realm is an important category in Chinese aesthetics.However,there are many debates about its meaning in the academia.The basic characteristic of realm is:authenticity,transcendence and freedom.Due to the authenticity of mind,it can illuminate itself and the world;due to the transcendence of the senses and the desire for knowledge,it is able to understand all things and unite heaven and man;due to no opposition to things,it can gain the freedom of a spiritual experience.In a certain sense,it can be said that the development of ancient Chinese aesthetics is a process of transmutation from the object image,image to poetic imagery,realm.This is a developing process not only from ob-ject to mind,but also from subject-object dichotomy to super-subject-object dichotomy,and the key to the realm lies in the fact that it is created and visualized by the mind,which transcends all the limitations.Through two ima-ges of bright moon and open boat,we can fully understand this characteristic of the realm.