This essay aims to analyze Chih-yi's process of practice and the confines of enlightenment, since his ordination to the period of his seclusion in Tien-tai, as the basis to comprehend Tien-tai's thought of Yuen-dun-chihguan. The academic field has emphasized much more on Tien-tai's thought and meanings, and those people whose research topic is Chih-kuan pay less attention on or even neglect Chih-yi's practice experience and the confines of his enlightenment. According to my research, his practice experience of Chih-kuan has profound impact upon his explanation about traditional Indian meditation and the construction of his own Tian-tai Yuan-dun-chi-kuan, no matter in content, methods, or the frame. This article divides Chih-yi's learning and practice process into four stages since his ordination to the period of his seclusion in Tien-tai. First, when he just became a monk, he lived in seclusion in Da-xien Mountain, holding the themes of faith and practice of Fa Hua as his main method; he had ever seen the appearance of his transcendence. Second, during the period of his learning, he followed Huei-shi's instruction. Under his guidance, Chih-yi got circle dharnani (旋陀羅尼) and had the proof of the phenomena of Elementary yet Skilful Means of Fa Hua San Mei (saddharma-pundarīka-samādhi). Third, in his adulthood, taking the order of his teacher, he went to Jin-ling and delivered speeches on meditation. Meanwhile, Chih-yi wrote a meditation book mainly on ”The Order of Entering the Gate of Meditation”, because his enlightenment experience of meditation based on the non-step-by-step method brought him into the step-by-step meditation refines. Fourth, during the period of his seclusion in Tien-tai, living an ascetic life in Huading-fong, he ever met a magical monk, who told him the dharma and supported him. Furthermore, Chih-yi applied this experience and enlightenment of perceiving the Truth as the basis to write ”Mo He Zhi Kuan”, the representative work of Tien-tai sect's Yuen-Dun-Zhi-Kuan. Based on the above analysis and compared with the classification of the three main practices of Mahayana Buddhism made by Nāgārjuna, we know Chih-yi's experience of Zhi-Kuan practice and enlightened refines belongs to Mahayana practice methods - mainly the themes of faith & practice and wisdom & understanding. This is also the origin of the thought - ”growing the complete belief” and ”developing the complete practice” - in ”Mo He Zhi Kuan”.