ObjectiveCollege student interns frequently experience transitional stress as they navigate the shift from campus life to internship environments. Coping strategies for this transition have garnered attention within the field of organizational behavior. However, the current literature remains insufficient in examining the contingency mechanisms of internal psychological resources and external organizational support. Grounded in the Conservation of Resources Theory, this study aims to construct and test a moderated parallel dual-mediation model to elucidate how Physical and mental health (PMH) be associated with the divergent pathways linking job stress (JS) to job performance (JP).MethodsThis study employed partial least squares structural equation modeling (PLS-SEM) and bootstrapping (with 5,000 resampling iterations) to perform empirical tests and simple slope analyses on data collected from 464 interns in Guangxi Province, China.ResultsThe results indicate that the direct effect of JS on JP was not significant; however, a significant parallel mediating effect was observed through psychological contract (PC) and perceived organizational support (POS). A core finding of this study is that PMH was associated with a divergent moderation pattern across the dual mediation paths. Specifically, when individuals’ PMH levels were low, the PC pathway was significantly stronger; conversely, when PMH levels were high, the POS pathway became dominant, effectively translating external resources into performance. In conclusion, this study extends existing stress-performance frameworks by demonstrating that the mechanism through which JS be associated with performance is contingent on individuals’ PMH, offering new insight into interns’ resource allocation preferences under varying health conditions.ConclusionThis research expands the application boundaries of Conservation of Resources theory within the realm of occupational health and provides an empirical foundation for organizations to adopt “health-first” and “differentiated intervention” human resource management strategies.