The purpose of this study was to investigate the moderating role of psychological capital in the effect of performance appraisal policies on job satisfaction, turnover and job performance among the employees of automotive companies in Tehran. The research design descriptive-correlative research. The statistical population consisted of staffs of Tehran’, s automotive companies. According to Cochran formula, the sample size was 150 staffs, that they selected by using multi-stage cluster sampling. They completed Performance Appraisal Policies (Poon, 2004), Psychological Capital (Luthans, Youssef & Avoli, 2007), Minnesota Job Satisfaction (Weiss et al., 1967), Employee’, s Intention to Turnover (Jenny Keynes & Tomlinson, 2012) and Job Performance (Paterson, 1992) questionnaires. Data were analyzed using by hierarchical regression analyses. The results of correlation analysis showed that motivational performance appraisal policies had positive significant effects on job satisfaction, and job performance, and negative significant effect on turnover. Also, punitive performance appraisal policies had negative significant effect on job satisfaction, but its effects on job performance and turnover were not significant. The results of the hierarchical regression analysis also showed that psychological capital moderates the relationship between punitive performance appraisal policies and job satisfaction. Therefore, the greater the employees' psychological capital, the more satisfied they are with their job, they perform better and are less likely to quit their jobs. Also, punitive policies of performance appraisal less affect their job satisfaction.