The author, focusing on Mencius, Chang Tsai, Cheng Ming-tao and DongHak, draws acomparison between Chinese Confucianism and the ecophilosophical meanings of DongHak. Firstof all, this paper pays attention to 'acting nature's non-action', which is permeated through thedoctrine on mind & nature and the doctrine on cultivation of Mencius. It also demonstrates thecorrelation between agricultural civilization and 'acting nature's non-action'. Secondly, this studyinvestigates how the ideas of harmonious relationship between nature and man that wasformulated in pre-Qin dynasty, was more established in North Song dynasty. Specifically, itanalyzes the division of 'the nature of heaven(TienXing)' and the human nature in the thoughts ofChang Tsai, who invented the term called 'the unity of heaven and man'. Furthermore, it looksinto the weak point of Cheng Ming-tao's idea, which insisted the unity of 'principle ofproducing(Sheng Li)' and 'benevolence(Jen)'. Finally, this paper inspects closely the ecophilophicalmeanings of DongHak, which criticized and inherited Confucianism in order to find out thesignificance and limitation inside it. In spite of the fact that the DongHak accepts the concept ofnature(Xing) and unity of heaven and man of Neo-Confucianism, it clearly shows the differencebetween DongHak and Neo-Confucianism in that DongHak declares the subjectivity ofheaven(Tien), and criticized doctrine on priority or posteriority of principle(Li) and material force(Qi)with the concept of Great Qi. Moreover, it finds that Lee Don-Hwa's 'YinGanGyeuk' concept hasmuch deeper ecophilosophical meanings than the traditional 'personality' concept. It also finds thatChoi Si-Hyung's 'Rice(Shik)' thought transformed problems on the desire into the things that hascosmological and ecological meanings.