The concept of "Zhong" is not only related to the governance concept of rulers of the Xi Zhou Dynasty, but also related to the origin of the thoughts of Confucian moderation. Zai Gong's interpretation of the "Zhong" fully embodied the institutional meanings of "Zhong", and made up for the difficulties in the study of the "Zhong" concept in the Xi Zhou Dynasty. From the current historical data, the main connotation of the "Zhong" of the Xi Zhou Dynasty contained the ruling thought of "yi Shi Zhong yi wan bang", the concept of "moderate criminal law" and the view of "Zhong de". The clarification of the connotation of the "Zhong" of the Xi Zhou Dynasty, not only realized the unity of name and reality, but also showed its origin relationship with the early Confucianism. With distinct political attributes, the concept of "Zhong" of Xi Zhou Dynasty has been passed down from generation to generation.