As an independent subject, TCM psychology appeared in 1980s, but it could be traced back to the book, the Inner Canon of Huangdi (Huangdineijing) formed in Qin and Han Dynasties. Physicians in the later generations developed TCM psychology based on that occurred in the Inner Canon of Huangdi, which made it became mature gradually, and Sun Simiao was one representative figure among them. The fundamental features of TCM psychological theory of Sun Simiao are summarized here.