A Confucian scholar, Kang Youwei, living in the late Qing period imagined a future utopian society called datong which eliminated all social distinctions. To illustrate it, he borrowed and developed the theory of the Three Ages, which first appeared in the Confucian classic Gongyang Commentary on the Spring and Autumn Annals, as well as in the theory of human nature in the Han dynasty. However, one of his students, Chen Huanzhang, made a new explanation of the “Liyun” chapter that greatly differed from his teacher. According to him, datong was a society committed to “preserving social relations”. The different understandings of datong reveals two different patterns of social relations in Confucianism. Besides the traditional wulun pattern, Kang Youwei offered another possible pattern. Although it proved to be a failure in practice, as a theory that discovered many hidden traditions in Confucianism, Kang Youwei’s datong theory is worthy of attention.