The wireless mesh network is one of the most promising networks because of its huge potential of industrial application. Multi-path routing protocol which is used in wireless mesh networks can have plenty of benefits such as fault tolerance and improved security, high bandwidth and better load balance. However, how to stimulate each node to cooperate with others in a wireless mesh network that use a multi-path routing protocol still has not been well addressed. In this paper, we propose a reputation-based system for the wireless mesh network using a multi-path routing protocol that stimulates each node in different paths to forward packets from others. When using our reputation system, it can detect misbehaving nodes whose reputation values are below a threshold. In this way, our reputation system can provide an incentive for the misbehaving nodes to behave honestly. Experiments have shown that our reputation system is very effective in detecting misbehaving node and increasing average throughput in the whole network.