本文從本體之性與主體之心如何可能合一的角度考察分析了《大乘起信論》的心性論模式。體、相、用「三大」說是《起信論》之本體論的核心內容，而「眾生心」所蘊含的主體性原理是染法之所以生起與還滅以及真如與無明之所以可能互熏的另一重要理論前提。這樣的兩條原理的統一，便構成了《大乘起信論》心性思想的重要特徵。

　　　　　This 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. This 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.