Although the Zone of Proximal Development (ZPD) theory has been widely applied to second language acquisition and foreign language teaching research, there are still misunderstandings and controversies. To further clarify relevant concepts and present problems in the existing research, this article employs a scoping review research method, retrieving and screening 107 SSCI and A&HCI related research articles since 1994, and nearly 10 domestic core literature articles, to conduct content and methodological analysis. It is found that large differences exist in the interpretation of ZPD, unclear boundaries between related concepts, insufficient connection between theory and practice, and the research methods to be optimized. Furthermore, it proposes that future research should focus on the ontological study of ZPD theory, the influencing factors of second language development within the ZPD, and dynamic assessment based on ZPD.