Abstract： Humility is a traditional virtue in China, however, the effectiveness of humility has been questioned in modern society. For example, by expressing humility, one’s strength and contribution may not be recognized by others. Although the traditional view requires us to show humility, however, the modern view indicates that if someone expresses humility, he/she may not get deserved reputation. Meanwhile, sometimes followers may regard leaders’ humbleness as weakness because followers need powerful leaders to guide them. The paradox of traditional and modern views of humility raises leaders’ concern about whether and how to display humility in workplace. Based on interpersonal relationship perspective, this research aims to examine the effect of leader humility on employee organizational citizenship behavior, as well as the role of inferred leader humility motives during this process. Instead of focusing on the formal relationship between leader and follower, we proposed that humble leaders would be more attractive to followers and would be easier to form a good interpersonal relationship with followers. Meanwhile, we proposed that when followers inferred different motives of leader-expressed humility, the positive relationship between leader humility and relational closeness would be weakened or strengthened. In order to test our hypothesized model, we conducted a time-lagged leader-member matching questionnaire design. Our sample came from 13 big companies located in Wuhan or Xiangyang, which resulted in 295 leader-followers dyads. To reducing common method bias, leader humility, inferred leader humility motives and demographic variables was measured in time 1. 7 weeks later, we measured relational closeness and LMX from followers and we measured voice behavior and helping behavior from leaders. Because leader humility was embedded in teams, we used hierarchical linear regression to analysis the data. Meanwhile, to test the indirect effect of relational closeness in relationship between leader humility and employee organizational citizenship behavior, bootstrapping method was also adopted. Results showed that: (1) after controlling leader-member exchange, leader humility was positively related to relational closeness. (2) Leader humility could enhance followers’ voice and helping behavior. (3) Relational closeness mediated the relationship between leader humility and followers’ voice and helping behavior. (4) When follower inferred leader humility’s impression management motive was high, the positive relationship between leader humility and relational closeness would be weakened. However, the moderation effect of follower inferred leader humility performance enhancement motives on relationship between leader humility and relational closeness was not significant. The present research makes several contributions to leader humility literature. By examining the positive effect of leader humility on follower OCB, this research proves the effectiveness of leader humility further. Moreover, this study confirmed the mediating role of relational closeness as well as its boundary conditions. As to the practical implications, this research suggested that leaders could show more humility in workplace to trigger followers to do more organizational citizenship behavior. However, at the same time, leaders should realize that if their humility was motivated by impression management, the positive effect of leader humility would be weakened.