LiliBoulanger was an important composer of early twentieth centry French music. Although she had an early death due to Crohn‟s Disease at the age of twenty-four, she completed more the fifty pieces.Also she can considerate a productive composer. Her compositional style represents a development and mastery of musical techniques of the great composers of her time including Fauré, Debussy and Wagner combined with her own creative expression. Through her music, we can find vivid evidence of her intelligence, creativity, and artistic growth. Her musical and personal qualities were extraordinary.This essay will discuss her mature compositional style, specifically as it is reflectedin her song cycle, Clairières dans le ciel. The text will be examined in conjunction with the literary movement of symbolism in 20thcentury France and thesymbolist poet, Francis Jammes, with special attention to the composer‟s personal identification with the poetry. Considerations of the musical setting ofthe cycle will include the melodic style as it relates to the text, the harmonic idiom and its relation to the poetry, rhythmic and metrical devices use, formal devices and the relationship of the piano accompaniment and the voice.We can find that Lili get effortto put the poetand music toghther. The music of this song cycle is more abundant in form,dramatic tensionand expression.