In the first half of the 20th century, American left-wing politics has given rise to a large number of literature classic works and writers. Mary McCarthy is one of them, her literary creation is especially striking. Her works can enter classic for four main reasons: Firstly, the special history of the United States made her legendary life and outstanding literary creation; Secondly, the female images which she created not only challenged the patriarchal consciousness in left-wing culture camp, but also changed American realism literature of women in traditionality, showing distinct characteristics of the times. Thirdly, from two aspects of “truly ontology” and “relative ontology” the novels have provided huge reading space for the readers with special artistic tension; Fourthly, her autobiographical novels can face life and pay attention to the reader’s “centripetal reading”, which contains rich classic elements. The four points above are the important reasons for her to enter the ranks of the classic writers.