“Ratnagotravibhago Mahayanottaratantra sastra”（Uttaratantra）is a book that contained the most part of the tathagata-garbha thought .In its chapter Ⅵ, there are 9 metaphors of klesa. I tried to systematically collect the klesa philosophy by discussing it. In tathagata-garbha philosophy , the klesa is not an original element. All sentient bings’ buddha-nature will never be polluted and finally they will be able to attain to enlightenment. Therefore, the discussion for the path to eliminate all kinds of klesa is meaningful. In the first chapter, I introduced the reasons why I chose this subject , the methods for research and the central content of every chapter. In chapter 2 “The review of Uttaratantra” as a literature, the year it was written, its title, its Sanskrit texts and its Chinese and Tibetan translations, its authors and translators were discussed in detail. In charapter 3 “The klesa philosophy in Uttaratantra”, the differences between tathagata-garba and buddha-dhatu, the definitions and synonyms of klesa, the discussion of the klea in “Kath-vatthu”, the kinds of klea and its characteristics were discussed as well. In chapter 4 “How does the klesa appear and how is the klesa destroyed ?”, the appearance of klesa, the definitions of the thirty-seven aspects of the path to enlightenment, four ways for icchantikas , tirthikas, sravakas and pratyekabuddhas to eliminate klesa, the paths for bodhisattvas to destroy the klesa were discussed. Chapter 5 is the final concluding chapter of this thesis.
