This article probes Liang Shu-ming’s theory of human nature in his sunset of life mainly according to his most important work──The Mind and the Life──to elaborate the change of his thinking and his final idea of human nature. This article accordingly analyzes four topics: first, it focuses on his research methodology and points out that Liang was good at applying modern science, in particular, Darwinian theory of evolution and Marxism, so that he opened up a new path to make a study of human nature. Second, it elaborates Liang’s point of view toward the three characteristics of the voluntariness, agileness, and foresight of the human mind. Third, it analyzes the notion of self consciousness which is the most critical and basic capacity in the theory of human nature. Fourth, it looks into the reason why Liang valued self-consciousness from his personal experience, and explains his change by the difference his conception of self-consciousness from his earlier one.