Work stress and anxiety are major problems faced by graduate nursing students. Research on the relationships between these factors has the potential to improve the psychological state of graduate nursing students. This study gathered a valid sample of 321 graduate nursing students and performed structural equation modeling and multiple regression to test the proposed research model. The study used the Clinician Work Stress Scale, Psychological Capital Scale, Social Support Rating Scale, and State-Trait Anxiety Scale to survey the sample. Correlation analysis showed that job stress was significantly correlated with psychological capital (r= −0.46,P< .01), social support (r= −0.21,P< .01), and anxiety (r= 0.47,P< .01). Psychological capital (r= −0.56,P< .01) and social support (r= −0.43,P< .01) were significantly correlated with anxiety. The results of the path analysis showed that psychological capital (0.21, 95% confidence interval: 0.19–0.39) and social support (0.07, 95% CI: 0.02–0.15) played a mediating role in the relationship between job stress and anxiety, and the mediating effect accounted for a percentage of the total effect (51.85%). There is a direct relationship between clinical social work stress and anxiety among nursing postgraduates. Anxiety is significantly reduced through the intermediary effects of psychological capital and social support.