Abstract: To further reduce the energy consumption of wireless sensor node using B-MAC protocol, receiving, sending, monitoring, sleeping current consumption and time characteristics of wireless communication module were practically tested. According to the characteristics of asynchronous MAC protocol, network load parameters have been subdivided into four parameters: sending interval, receiving interval, the number of sending bytes each time, the number of receiving bytes each time of node and consider the probability of node status when it receives signal to build the communication energy consumption model. The optimal analytical solution of the communication energy consumption model was given. It makes energy consumption parameter to be optimal in different network load and transmission interval. Experimental results show that energy optimal parameters B-MAC protocol proposed in this paper consumes less energy than ordinary B-MAC protocol. It obviously reduces energy consumption during communication process of WSN nodes and extends the working life of the node.