Abstract: Based on expectancy theory, this paper studies the relationship between power need and organizational citizenship behavior of civil servants in the Chinese context. With a survey of 423 civil servants, the paper performs a regression analysis which reveals that the power need of civil servant will significantly affect the organizational citizenship behavior in a positive way. Therefore, higher power need leads to a better organizational citizenship behavior. The study further introduces the theory of organizational politics and impression management, suggesting that the procedural justice of the promotion negatively moderates the relationship between the power need and the organizational citizenship behavior. That is, when the civil servants' procedural justice of promotion is high, the relationship between power need and organizational citizenship behavior will be weaker.