Master Zhangan Guanding’s was the Fifth Patriarch of the Tiantai School. He was the actual organizer of the three major works of Tiantai: The Profound Meaning of the Sublime Dharma of the Lotus Sūtra, The Words and Phrases of Sublime Dharma of the Lotus Sūtra, and The Great Calming and Contemplation. His life was the organisation of the discourses of Master Zhizhe and the historical materials of the Tiantai School. Later generations only commended Master Zhangan for the collation and annotation of Master Zhizhe’s achievements. Few studies have pointed out how Master Zhangan had uniquely surpassed or exceeded his teacher in the teachings. Obviously, the Fifth Patriarch Master Zhangan’s ideological characteristics of Tiantai Studies have not yet received the attention in academic circles. If we explore the theory and thoughts of Master Zhangan, the only works that can express his own thoughts are probably The Profound Meaning of the Mahāparinirvāṇa Sūtra and The Commentary on the Mahāparinirvāṇa Sūtra. As The Mahāparinirvāṇa Sūtra already had a great volume of works and theories written by the Nirvāṇa masters during the Southern and Northern Dynasties, and Master Zhizhe did not have any discourses about it in his life, therefore modern scholars have not had much research on Master Zhangan's annotation thoughts on The Mahāparinirvāṇa Sūtra. In the process of going through Master Zhangan’s The Commentary on the Mahāparinirvāṇa Sūtra, I began to notice that Master Zhangan’s interpretation of the sevenfold two truths of Master Zhizhe was expertly applied to the textual expositions of “The Worldly Truth” and the “The Ultimate Truth” in The Mahāparinirvāṇa Sūtra. This formed the terms “single middle and complex middle”, which is different from the sevenfold two truths of Master Zhizhe. This stimulated the criticism of the commentary of Master Zhangan by the modern scholar Mr. Mou Zongshan. At the same time reviewing the interpretation of the later generations of the two Masters of the Tiantai School, Jingxi Zhanran and Gushan Zhiyuan, we have found another proposition. The possible impact of these different interpretations on the study and research of the thoughts on the Tiantai School is one of the focuses of this dissertation. Secondly, although Master Zhizhe has never lectured on The Mahāparinirvāṇa Sūtra, in the section on “Section Five, the explanation of the sublime practice” in last column of the Third Fascicle to the last column of the Fourth Fascicle of The Profound Meaning of the Lotus Sūtra, it is in accordance with the “five practices” of The Mahāparinirvāṇa Sūtra. This regards the distinct and perfect practices of the sublime dharma. Master Zhangan in his annotation of the text used “sequential gradual practice” and “non-sequential gradual practice”. We w