The Four Books(Si Shu)was attached great importance to literati and officialdom from Selected Commentary of the Four Books(Si Shu Ji Zhu)edited by Zhu Xi during the Song Dynasty was published. Among the increasingly works of the interpretation on the Four Books there is no lack of Buddhist monks' ones; Ou Yi Zhi Xu, lived between the late Ming Dynasty and the early Qing Dynasty, whose Ou Yi's Interpretation on the Four Books(Si Shu Ou Yi Jie)is one of the works. Zhi Xu's Ou Interpretation on the Four Books(Si Shu Ou Yi Jie)was written for preaching Buddhism by interpreting the Four Books, he says directly that his motive of writing is to clarify the Buddhist ”Primary Real Principle”(Di Yi Yi Di); consequently, his interpretation is widely different from Confucian thread of thought. This essay will take The Interpretation of Great Learning: Denoting immediately the ultimate source of soul (Da Xue Zhi Zhi)-part of Ou Yi's Interpretation on the Four Books (Si Shu Ou Yi Jie)-as an object of study, and analyze how Zhi Xu connected the significance of Confucian Great Learning (Da Xue) with Buddhist study on essence of soul.