Abstract: The "mellow and unrestrained", aesthetic style theory of Chinese literature has not been noticed by the academic community. The theory system was formed in the ontology of "the righteousness of hao", the work theory of "nurturing to enrich" and the Confucianism value theory constructed by XU Yuanwen's preface to Mr. WANG Yangming's anthology in the early Qing Dynasty. Based on XU's theory, we find a development process: created by HAN Yu, developed by SU Shi and ZHU Xi and constructed by XU Yuanwen.At the same time, XU Yuanwen was assisted by WEI Xi and LI Guangdi. Through differentiate and analyse with "Hong Er Si" and "Moderate Beauty", we find "mellow and unrestrained", the same as "moderate beauty", is the basic aesthetic style theory of Confucian literature.