Fostering students' scientific literacy is a key goal of science education, with understanding the nature of scientific inquiry (NOSI) as a central component. Achieving this goal requires teachers to possess adequate knowledge in this area. However, assessments indicate that pre-service science teachers (PSTs) have not yet developed comprehensive understandings of NOSI. To address this, this study integrated the 5E model with explicit-reflective NOSI teaching within a science methods course. Quasi-experimental pretest-posttest design was employed. The Views About Scientific Inquiry (VASI) questionnaire was used to assess PSTs' understanding of NOSI. Before the study, most PSTs demonstrated naive or mixed views on various aspects of NOSI. Following the intervention, PSTs' understandings of all aspects improved significantly. Among these, more than half of the PSTs demonstrated informed understandings in four aspects: "begin with questions," "multiple methods," "questions guide procedures," and "conclusions must be consistent with data." These findings highlight the effectiveness of integrating the 5E model with explicit-reflective NOSI teaching in enhancing PSTs' understanding of NOSI. As one of the early attempts, this study lays a foundation for future research on applying the 5E model to NOSI teaching across diverse educational settings and highlights the need for its integration into teacher education curricula and professional development programs.