The Yun Yu Yang Ch'iu is a shih hua 詩話 ("poetry criticism") by Ko Li- fang, a Southern Sung literary critic. The work, which contains20 vol umes (approximately 90 thousand characters), focuses on poetry from the T'ang and Sung dynasties. The present paper discusses the following themes of the Yun Yu Yang Ch'iu: (1) Poetic principles: natural, self-existent, elegantly simple, graceful and farsighted. (2) Poetic techniques: free-flowing writing style, runon lines, avoid ance of repetition, eight-line stanzas, changing and imitating. (3) Commentary on Tang poetry (Li Pai 李白, Tu Fu 杜甫, etc.) (4) Commentary on Sung poetry (Yen Su 晏殊, Wang An-hsi 王安石, Huang Ting-chien 黃 庭堅 etc.)