The Biography of ther Buddha is the biography of Shakyamuni, which records the deeds of the Buddha in his life. In Buddhist texts, sutras and vinaya are books that systematically describe the deeds of the Buddha. However the records of sastras are relatively fragmentary and the deeds of the Buddha listed by the commentators are mostly used to distinguish and unearth the profound meaning of the conviction. The formats of sastra is different from that of sutras and vinaya: the major difference lies in the fact that the commentators consider the various deeds of the Buddha by focusing on rationality and free thinking, and they set up issues first, subsequently using questions and answers to manifest the deep meanings hidden in the various texts . In the present work, this article uses the four themes: life-preservation and life-extinction, the life-extinction of Buddha’s two major disciples, the Buddha attaining Parinirvana, and the Davi to examine of the commentator's interpretation of these events and their characteristics. Through the discussion of the four items, the author found that even if the Sarvastivada insists of a real Buddha in the human world, commentators have tended towards idealized interpretations of the Buddha’s Nirvana, whether as longevity or as surrender, the unsatisfactory matter of the twosage disciples’ death, the Buddha’s Nirvana in the border area of the small town Kushinagar, and even the Davi dharma meeting of the Buddha’s deceased body. This frequent idealization shows an emotional side of the commentators.