The author of many poems dealing with the conditions of the Negro, Countee Cullen was criticized by many of his contemporaries for his adherence to traditional form in his poetry; they felt that this form was not appropriate for the expression of the racial issues.  Nevertheless, his figurative language and sonnet forms express an emotionalism that is felt by readers. Langston Hughes stated that Cullen's "The Black Christ" was the greatest poem he ever read.

Besides addressing issues of race, in terms of the beauty of being black the one hand and the effects of racism on the ohter, Cullen also contributed to the Harlem Renaissance a sense of poetry as a tradition. That is, although his topics were often controversial, he wrote many of his poems in the form of the Shakespearean sonnet, and critics often discuss the influence of English Romantic poets, such as William Wordsworth and William Blake on his verse.  In this way, he brought a legitimacy to the Harlem Renaissance, providing it a piece of white culture, which he converted to his own radical use. His sonnet "The Black Christ," for example, which is written in a traditional sonnet form, usually reserved for topics of love or other elevated ideas, compares a black man who is lynched, hanging from a tree, to Christ: this mixture of irreverence toward and celebration of tradition provided a unique tone to the literature of the Harlem Renaissance.

countee cullenwhat was his influence on harlem reniassance? 

Viewing poetry in a very traditional manner, Countee Cullen writes almost all his poetry in standard verse forms with fixed meters and rhyme schemes.  Like his model, John Keats, the English Romantic, Cullen felt that poetry should celebrate beauty and truth.

While he wanted to be recognized as a man of literature because of his kill, not his race, Cullen, nevertheless, found himself immersed in his color and the problems of his race.  The titles of some of his volumes of poetry denote this involvement:  Color, Copper Sun, and The Ballad of the Brown Girl.  Certainly, Countee Cullen was the most popular of the Harlem Renaissance poets.

countee cullenwhat was his influence on harlem reniassance? 

The poet is widely recognized and anthologized and is one of the names that anchors the poetry side of the Harlem Renaissance along with Langston Hughes.

There are sources available where you may want to look for more information:

http://www.enotes.com/countee-cullen-criticism/cullen-countee

http://www.enotes.com/countee-cullen-criticism/cullen-countee/principal-works