BACKGROUND The job performance of individual employees determines the overall performance of an organization, and organizational support is known as an important resource at the organizational level to enhance job performance. Although nursing scholars have confirmed the crucial role of organizational support in enhancing job performance, there are no studies on whether psychological capital and organizational identification mediate the association between organizational support and job performance. The purpose of this study is to investigate the influence of organizational support, psychological capital, and organizational identification on nurses' job performance. METHODS A cross-sectional survey was conducted among 455 nurses from 21 public hospitals in China. Instruments were perceived organizational support scale, task performance scale, contextual performance scale, Nurse Psychological Capital Questionnaire, and Organizational Identification Questionnaire. Survey data were analyzed using SPSS and AMOS, and hypotheses were tested using path model analysis. RESULTS Nurses' perceived organizational support, psychological capital, organizational identification, and task/contextual performance were positively correlated in every two variables. Psychological capital played an important mediating role in perceived organizational support and task/contextual performance, as well as organizational identification. The multi-mediating effect of psychological capital and organizational identification on the relationship between organizational support and task/contextual performance were 0.14 and 0.25, respectively. CONCLUSIONS There was a positive correlation between organizational support and job performance among nurses. Psychological support, organizational identification and contextual performance played a chain mediation role in the relationship between organizational support on task performance in nurses. Nursing managers should pay more attention to enhancing nurses' psychological capital and organizational identification through effective interventions to improve nurses' job performance.