"Enlightenment"(wu) is a moral cognitive practice that aims to elevate individuals' moral realms under a comprehensive effect of moral emotions, moral rationality and moral actions. It constitutes a unique thinking mode in traditional Chinese moral philosophy. Semantically, the Chinese word "wu" originally means physical "awakening", and then it extends to mean spiritual "enlightenment". By examining the relationship between "enlightenment", "Dao" and "body"(ti), we find out that "Dao" is the purpose of "enlightenment", while "body" and "enlightenment" manifest a common cognitive method in Confucianism. WANG Yang-ming's personal experience of the "enlightenment of Dao" reveals "enlightenment" as the thinking mode in traditional Chinese moral philosophy:taking the "Dao of becoming a sage" as its purpose, experiencing "doubt", "puzzlement", "encountering", "thoroughness" and "proving" step by step, and eventually "realizing the Dao".