The research was aim to investigate the relationship between workplace friendships and workload, and the mediation effect of organizational citizenship behavior (OCB) on the relationship of workplace friendships and workload, as well as the moderating effect of proactive personality on OCB and workload. This study collected data from web- and paper-based questionnaire survey, and 256 valid questionnaires were collected. After collecting the data, this study use hierarchical regression analysis to analyze the data. The results suggested that: (1) workplace friendships had a positive impact on OCB, (2) OCB had a positive effect on workload, (3) OCB mediated the relationship between workplace friendships and workload, (4) proactive personality has a positive moderating effect in the relationship between OCB and workload. Based on the results found from this study, they provide practical implications for enterprises.