Scholars who research corpora and its pedagogical implications differ in their views; some believe that corpora should be integrated into teaching practices and teacher training programs, while others caution against such implementations and suggest that critical examinations of corpora use in classroom needs to be in place. To better understand the pedagogical implication of corpora, this study uses surveys and interviews to explore ten pre-service ESL teachers’ perception of using Corpus of Contemporary American English (COCA) in ESL classrooms. The result suggests that COCA is beneficial for ESL teachers in designing classroom materials and developing digital literacy; however, our finding also indicates that learners' L2 proficiency and logistics need to be taken into consideration when using COCA in classrooms.