Real-time applications such as multimedia applications have high requirements on bandwidth, delay, jitter etc, which requires WMN (Wireless Mesh Networks) to support QoS. QoS routing is crucial to provide QoS. This paper focuses on QoS routing with bandwidth constraint in multi-radio multi-channel WMN, and proposes a new multi-metric and a QoS routing protocol MMQR. The routing metric has two advantages. First, it replaces the transmission rate of ETT with available bandwidth so that the nodes with light load are more likely to be selected. Second, it takes the channel diversity into account and assigns a weight to each link according to the channels of links within the range of three hops. MMQR addresses the problems that real QoS cannot be satisfied due to interference and congestion and the link doesn't work because of node failure.