The purpose of this study is to examine how participation in the professional learning community of teachers influences through understanding and reorganization of the curriculum in activating learner-centered instruction in vocational high schools as students are emphasized as the subject of education. To achieve the purpose, a survey was conducted on class teachers at 514 vocational high schools, and a PROCESS macro program was used to verify the dual-mediated effect of the curriculum understanding and reorganization in the relationship between professional learning community and learner-centered instruction. As a result, it was found that the professional learning community had a direct influence on learner-centered instruction and teachers understanding and reorganization of the curriculum. In addition, it was found that the professional learning community of teachers not only affected learner-centered instruction by mediating curriculum understanding and reorganization, but also affected learner-centered instruction by sequentially mediating curriculum understanding and reorganization. As implications of these results, there is a need to prepare a plan for continuous support of the school for revitalization of the professional learning community of teacher and revitalization of curriculum understanding and reorganization. It was suggested that attemps should be made such as comparing the effects of various forms of the professional learning community of teacher or using qualitative research methodologies.