Wireless mesh network is a communications network made up of radio nodes organized in a mesh topology. Aimed to multi-channel assignment in wireless mesh network, a new MAC scheme is proposed named MRMC-MAC. MRMC-MAC scheme includes default receiver channel allocation, distribution of main switchable channels, node communication and the update of main switchable channels. In MRMC-MAC, channel allocation is on the basis of a received load-based allocation algorithm. The received load is defined as priority parameter in channel allocation, which can ensure that heaviest received load node has the highest priority to get the light load channel and light received load nodes share the same default receiver channel. Thus, the load between the channels can be balanced. In addition, the hidden terminal problem in multi-channel multi-radio network is analyzed, and some solutions to solve the hidden terminal problem are presented. Simulation on MRMC-MAC is conducted using NCTUns 5.0 platform and the simulation results show that network capacity has been greatly improved in MRMC-MAC.