Abstract: The validity is the most important standard to judge a language test. And it aims to know whether the examiner has tested the content the designer intends to do. It is closely related with the test aim. The proper adjustment and perfection of amount design of CET-4’s writing, direction and forms can help to evaluate more scientifically and objectively the students’ writing abilities, and to improve the test validity of CET-4 writing as well as to exerted positive influence on teaching of English writing.