Abstract: The philosophy of perfect interfusion, put forward by Chihi, the defacto founder of Tiantai Sect, is the basis of Tiantai Buddhism. The paper summarizes Chihi's, perfect interfusion by reviewing the text structure and theoretical framework of The Lotus Sutra, the methodology and techniques to build his ideological system, and the contents and formation process of Buddhism philosophy.

Key words: philosophy of Perfect Interfusion, Tiantai Buddhism, real mark Buddha, middle way, The Lotus Sutra (Saddharmapundarika Sutra)