In recent years, the application of corpus in the field of language testing has been widely recognized, and its application potential and prospects have also attracted much attention. Based on this, first of all, the application of corpus in language testing was expounded from four aspects: test development, development of automatic scoring system, formulation of scoring scale and vocabulary formulation in examination syllabus;then, taking the construction of Chinese English learners' writing competence scale as an example, the application of corpus in the construction of writing competence scale was expounded;furthermore, the application prospects and limitations of corpus in language testing were analyzed. The rise of corpus research methods provides an effective way to improve the authenticity of language testing.