This dissertation studies the discussions on ghosts by the Neo-Confucians of the Song Dynasty, in particular Zhu Xi and Chen Chun. According to these thinkers, Gui (the ghost) refers to the deceased and represents the fading away of Qi (materials), and it is also part of the ancestor worship. Based on the typically Neo-Confucian interpretation of Li (principles) and Qi (materials), this dissertation demonstrates how Zhu and Chen explicated the idea of “Li persist on even though Qi fade away” by an articulation of their understanding of the ghost. The thesis consists of five chapters. The introduction summarizes previous works concerning Neo-Confucians’ discussion on Gui. It also briefly explains why the idea of Li and Qi is significant to the distinction between living people and ghosts as seen by Neo-Confucian thinkers. The definition of “Neo-Confucians” is briefly explained at the beginning of the introduction. Chapter one presents how Neo-Confucians apply the Qi theory to Gui, and their idea of an appropriate worship as intimately related to Qi, yet with its rationality lying with Li of human relations. Chapter two analyzes the Neo-Confucian idea of li gui (haunting ghosts) which is differentiated from the ghost in the ancestry worship system. For Neo-Confucians, li gui fail to understand the appropriate relation between Qi and Li and try to reject the fading away of Qi after death. In Chapter three, it is examined that Zhu Xi and Chen Chun’s opinion that living people play a role in the ghosts’ haunting because of their lack of knowledge of either Qi or Li, and suggest that they become the human form of “haunting ghosts” because of such a failure in understanding. In conclusion, the thesis suggests that the right way to live out the true potentiality of human beings is to accept the limitation of Qi but try to grasp the eternal Li through the observation of the movements of Qi. / published_or_final_version / Chinese / Master / Master of Philosophy