Abstract: Objective To explore the relationship between occupational stress and job performance and the mediating role of psychological capital.Methods Proportion allocation random sampling was used to investigate 400 psychiatrists from all the 1 571 psychiatrists in all the 18 psychiatric mental health centers in Liaoning province.SPSS17.0 statistical software was applied to perform statistical analyses and test study hypothesis.Results The total score of job performance scale was 78.09±10.85.Job performance had negative association with two domains(extrinsic and intrinsic efforts) of occupational stress,while psychological capital was positively associated with occupational stress.Perceived occupational stress explained 12.3% of variance in job performance and psychological capital explained 20.8% of variance in job performance.Conclusion Occupational stress and psychological capital have an important influence on psychiatrists' job performance and psychological capital has a mediating effect on the relationship between occupational stress and job performance.