The theory on human nature is an important constituent and the basic premise of the theoretical construction of Guo Xiang's metaphysics. He reset and deepened the basic connotation of human nature, bringing into it benevolence and rightness and potential, and distinguishing nature and emotion in order to deny acolasia. He accordingly rewrote Zhuangzi's view of xiaoyao, advocating a moderate xiaoyao. His theory of human nature fully embodied his reflection and critique of the fashion of his times, inspiring energetic and enterprising life. Guo Xiang's idea of a moderate xiaoyao gained its practical position in the Eastern Jin Dynasty. The noble-family politics, which was consistent with Guo Xiang's political ideas, promoted the change of mentality on the part of the gentry so as to guarantee the practice of Guo Xiang's metaphysics at both political and life dimensions. Guo Xiang's metaphysics laid an ideological foundation for the formation of aesthetic taste in the Eastern Jin Dynasty.