Cheng Yichuan's thought on mind and nature has abundant thinking connotation. The structure of mind in his thought is complex. Mind includes three factors-nature, xing and external things. Among them the factors of xing and external things decide the posteriority of mind. However, the nature is the essence of mind, which indicates mind has metaphysical nature. It is in this sense that Yichuan approves that mind, nature and li are identical. Based on the above, this paper also discusses the problem of good and evil and the problem of weifa in order to clarify the structure of Yichuan's thought on mind and nature.