The paper gives a systematic study on the theory of Mahayana in on the awakening of the faith. Its clue is how to unite the nature of ontology and the mind of subject. While the three greats—ontology,phenomenon and faction --are the basic content of the ontology in on the awakening of the faith, the subjective principle included in the “common mind” constitutes the premise which, as an important theory,considers it possible that the impure dhamma appears and disappears and the tathat and aridya affect each other. And the unity of the above-mentioned principles is considered the most important characteristic of the mind-nature thought in on the awakening of the faith.