Cheng Ming-dao's theory of heavenly principles, his theory of ontological nature and life and his theory about the cultivation of mind-nature were crucial to the latter development of Confucianism, in particular to the Hu Xiang School and the Lu-Wang doctrine of mind. Therefore, to interpret relevantly Cheng's theory of integration between heaven and man is crucial to the historical development of Confucian ontology and mind-nature theory and forms a solid theoretical foundation for the research on Neo-Confucianism. In view of Mo Zong-san and Tang Jun-yi's interpretations, we would explicate how Cheng's theory of integration inspires the ontological dimension and humane values of its latter development.