According to the social information process approach, we proposed a serial mediation model from humble leadership to knowledge sharing. The structural equation model on 537 elementary and secondary school teachers from 238 professional learning communities in China demonstrated that the positive association between teachers' perception of humble leadership in professional learning communities and teachers' knowledge sharing was mediated by teachers' psychological safety and psychological empowerment serially. Moreover, the parallel mediation effects of psychological safety and psychological empowerment were found. It indicates that humble leadership improves teachers' knowledge sharing in professional learning communities by ameliorating teachers' concern for taking interpersonal risks and improving teachers' psychological empowerment in sequence.