Influenced by the design principles of the layered network protocol stack, current MAC protocols in wireless sensor network usually resort to improving energy efficiency as a major energy saving means, with little considerations of load balance, which limits the network lifetime. In this paper, a forwarding election-based MAC protocol, FE-MAC, is proposed. By means of load balance improvement, energy is evenly consumed among nodes, and network lifetime is further extended. FE-MAC protocol adopts the forwarding election mechanism, in which nodes are organized to contend for the right of packet forwarding according to their residual energy, the more energy a node has, the more forwarding tasks it will take, and load balance and routing capability are realized. The experiments show that: compared with S-MAC and T-MAC, in wireless sensor networks of different scale, FE-MAC can prominently extend network lifetime, and the larger the number of nodes is, the better FE-MAC protocol performs. FE-MAC is more suitable to configuring large scale wireless sensor networks.