Abstract: Relation is the most fundamental form in which nature and human society come to existence. The relation between humans constitutes personality relation, the relation between the different things in nature constitutes non-personality relation, and the relation between humans and nature constitutes personalized relation. All relations are formed by two or more than two parties. They can only exist in relations, and their meaning can only be manifested in being viewed as objects in relations. Practicality, medium, and dynamic balance are the three particular characters of any relation. The relation ontology supports the formation of practical conceptions and the methodology system that conforms to logic in the process deduction.