As a key technology for next-generation wireless networking, wireless mesh networks (WMNs) should support the quality of service (QoS) because of its capability of integrating with other networks and providing various services. In this paper, the state-of-the-art QoS research on WMNs is presented. By analyzing the current QoS architectures, the QoS architecture on WMNs is discussed. To address the QoS issues below network layer, the research of recent years on the power control, wireless environment awareness, MAC(medium access control) protocol based on QoS, QoS routing, cross-layer design for QoS and other aspects is comprehensively summarized and deeply analyzed. At the end of this paper, future work of QoS on WMNs is proposed.