As a genre of folk song, the ballad is impersonal in that it often depicts something beyond the personal attitude or emotion of a poet. Yeats, to simplify the diction of his poetry, tried to use the metaphor of ballad, which is a material appropriate to human experience and instinct. As an important device of the ballads, the ‘refrain’ of his poetry is especially marked. The refrain (that is, verbal repetitions) may be a word or a line or groups of words or lines, and appears at the end of each stanza. In addition, Yeats’s use of the refrain is remarkable in his later poetry, particularly in The Winding Stair. The refrain may be without meanings, serving for some musical effect, as in some poems of the Elizabethan Age but it may give life to the language as Friedrich Schiller points out. This essay tries to divide the function of refrain into four types, despite the danger of making Yeats’s poetic range look limited. All the poems are not ruled by only one function but, in part, some poems appear to be with mixed functions. First, the refrain emphasizes poet’s theme through ironic meaning, as in the poems of ‘September 1913,’ and ‘‘The Curse of Cromwell’ and ‘The Three Bushes.’ Secondly, the refrain brings about mystery by the images of silent stillness, as in the poem of ‘Long-legged Fly’ and ‘The Apparitions.’ Thirdly, the refrain may give life to the language in conversion of the meaning, as in the poem of ‘What then?’ Fourthly, the refrain shows nonsense or meaningfulness, as in the poem of ‘The Pilgrim.’ This ‘nonsense’ speaks for his view of life in his later period, and reveals his willing acception of tragic nihilism.