To handle the problem of packet loss caused by the large number of retransmission times in the IEEE 802.11s-based wireless mesh network, a novel airtime link metrics algorithm based on maximum number of retransmission times was proposed according to the retransmission characteristics in the actual wireless network. Meanwhile, an improved Multi-root Hybrid Wireless Mesh Protocol (M-HWMP) based on tree-based rooting mechanism was proposed to alleviate the network congestion caused by the topology with single root node. This modified protocol can also improve the transmission performance of the edge node in some practical scenarios and ensure fairness of the use of wireless channel resources. Theory and simulation results showed that the improved algorithm and protocol can optimize the throughput and delay of different data flows in Wireless Mesh Network, and also can avoid network congestion to some extent.