In order to reduce couriers' unsafe behaviors caused by job burnout and effectively avoid safety accidents, this study aimed to explore the influencing factors and management countermeasures of couriers' unsafe behaviors based on the Stimulus-Organism-Response (SOR) theoretical framework, employing mixed research methods. Firstly, it integrated data from on-site interviews and questionnaires, and analyzed the action paths of work burnout and safety attitude on couriers' unsafe behaviors from the four-dimensional factors of man, machine, environment, and management. Secondly, it constructed a conceptual model that includes the four-dimensional factors (man, machine, environment, and management), work burnout, safety attitude, and unsafe behaviors. Finally, it used Smart PLS 4.0 software to verify the structural equation model and put forward corresponding management improvement strategies for the state, express enterprises, and couriers based on the analysis results. The results show that work burnout and safety attitude have a significant positive impact on couriers' unsafe behaviors. Among them, the four-dimensional factors of man, machine, environment, and management indirectly affect unsafe behaviors through the mediating role of work burnout; the three-dimensional factors of machine, environment, and management indirectly affect unsafe behaviors through the mediating role of safety attitude (p<0.05).