My research topic is a comparative study of Zhu Xi and Lu Jiuyuan's theories of mind. The study aims to examine the similarities and differences between their philosophies from the perspectives of theories of mind, ritual institutions, and comparisons among Confucianism, Buddhism, and Daoism. First, it conducts a systematic comparison of their philosophies at the ontological level through the relatively concrete and crucial category of mind. Second, it seeks to connect the comparison of their theories of mind with ritual thoughts and social practices, thereby exploring the functional dimension. Third, through close comparison, it offers new interpretations and reflections on certain established scholarly understandings of their thoughts.