Objective  To explore the mediation effect of psychological capital on the relationship between perceived organization support and job involvement among nurses.

  Methods  We conducted a survey among 536 nurses selected from a grade-A tertiary hospital in Harbin city between February and May 2018. The Perceived Organization Support Scale, Nurse Psychological Capital Scale and Utrecht Job Involvement Scale were used in the survey. Data analyses were performed with SPSS 24.0.

  Results  For the 510 nurses with valid information, the mean score of perceived organization support was 124.98 ± 21.51; the mean psychological capital domain scores were 25.43 ± 4.14 for self-efficiency, 23.45 ± 4.63 for hope, 26.26 ± 4.42 for tenacity, and 25.41 ± 4.49 for optimism, respectively; the mean job involvement score was 52.02 ± 21.00. The job involvement score differed significantly by age, marital status and working years (all P < 0.05) but not differed by professional title (P > 0.05). The perceived organization support was positively correlated with job involvement (P < 0.05). All the four psychological capital domains were positively correlated with job involvement and perceived organization support (P < 0.05 for all). The perceived organization support was a positive predictor for job involvement (β = 0.155, P < 0.05). Significant mediating effects of psychological capital domains on the correlation between perceived organization support and job involvement were observed, except for the domain of tenacity, with the effect values (95% confidence interval) of 0.086 (0.020 – 0.156) for self-efficiency, 0.126 (0.051 – 0.215) for hope, and 0.060 (0.010 – 0.109) for optimism, respectively.

  Conclusion  The perceived organization support could impact on job involvement directly and indirectly through the mediating effects of psychological capital domains including self-efficiency, hope and optimism among nurses.