Guide For The Perplexed in Institute of Music (Yüe Fu Zhi Mi 《樂府指迷》) by Shen Yi Fu (沈義父) is the first treatise specifically on composing Ci (詞) in the history of theory of Ci in Sung Dynasty, since its publication, the literati began to discuss the theory and practice of composing Ci. In the first chapter of the book, he indicates the four principles of composing Ci: 'The tonality should be harmonious, a inharmonious Ci is nothing but Shi (詩) of long and short sentences; the choices of words should be elegant, inelegant Ci amounts to the genre of vulgar song (Chan Ling 纏令); the using of words should not be too overt, overtness is too straight-forward without any sense of depth; the intent should not be too grand, grandeur will invite bizarreness and loss of graciousness.' The four points constitute the center of discussion in the book, therefore the four problems will be the foci of this essay. This essay has the following special points: firstly, the harmonious tonality theory of the book; secondly, the aesthetic tendency of adoration of classicism in the book; thirdly, the poetic perspective of using literary terms and allusions; fourthly, the emphasis on the main intent of the content should be with reserve. In this essay, the investigation of its modes of expressions and the content therein amongst the discourses of Ci will illustrate the significance and value of Guide For The Perplexed in Institute of Music in discourses of Ci in Sung Dynasty.