Abstract:With structural equation modeling, this paper explores the relationship between organizational ethical climate and organizational citizenship behavior (OCB), and the mediating role of employees’ trust in supervisor in this relationship. Using a sample of 1 133 employees from 30 companies in different industries, the results show that various ethical climates affect trust in supervisor and OCB differently. The Instrumental ethical climate has no significant impact on OCB, while the Caring and the Rules both have significant positive impact on it. Moreover, supervisory trust respectively plays a complete mediating role in the relationship between the Caring and OCB, and a partial mediating role between the Rules and it. In addition, the Instrumental has significantly negative impact on trust in supervisor.