Project-based learning (PBL) is a transformative approach to college education with the potential to develop comprehensive skills such as critical thinking, problem-solving, and teamwork. This study explores factors influencing the effectiveness of PBL and proposes strategies for its enhancement among Chinese college students. Utilizing the Input-Environment-Output (IEO) model as a theoretical framework, we conducted an empirical analysis of PBL outcomes and their determinants. The study employed advanced data analysis techniques, including structural equation modeling (SEM), to demonstrate the positive impact of PBL on knowledge integration, project skills, and self-efficacy. The effectiveness of PBL, however, is influenced by various factors, including instructional design, teacher guidance, student participation, and the disciplinary and institutional contexts. Based on a survey of 553 Chinese college students, the findings suggest that targeted improvements in these areas can optimize PBL to better meet students' educational needs. The results provide actionable insights for educators and policymakers on enhancing PBL strategies to foster a more engaging and effective learning environment.