Abstract: In Kant's philosophical system, the aesthetic activities belong to reflective judgment, the characteristic of which is their highlighting of human freedom, which is expressed as the bottom-up return to reason through imagination. When imagination and intellectuality are in a state of freedom and harmony, the material is consistent with the rational form, resulting in beauty; when the material stimulates and damages the formation of rationality, ugliness arises. Aesthetical judgement is different from the knowledge of the provisions of the judgement; it is a dialectical movement between freedom and necessity, highlighting the integrity of the rational framework, rather than a specific concept of intellectual bondage. Knowledge and aesthetic are both under the scope of reason, therefore the acquisition of knowledge and aesthetic ability are mutually beneficial.