Abstract: Channel assignment is a NP hard problem in wireless Mesh networks.To solve the problem,a heuristic channel assignment algorithm based on topology optimizing and interference avoiding is proposed.A network topology optimization algorithm based on maximum-flow minimum-cut is proposed in first to get relatively simple topology.Then each link is assigned a channel under the constraints of interface number of node,available channels and link utilization.Experimentcal results show that the proposed algorithm can avoid channel allocation chain reaction and can achieve fairly good performance and throughput.