The paper presents a new WLAN (wireless local area network) MAC protocol, probability detection CSMA with monitoring for WSNs MAC protocol. Analyzes and builds the corresponding mathematical model using average cycle method, and get the mathematical expressions of systemic throughput and the life cycle of terminal nodes of the probability detection CSMA with monitoring for WSNs MAC protocol through a rigorous mathematical derivation. Simulation results show that the probability detection CSMA with monitoring for WSNs MAC protocol due to join the monitoring signal, resulting in the decrease of systemic throughput, but reduces the collision probability. Meanwhile, under the control of the protocol, the systemic throughput and utilization rate has a higher value in the light loads, then avoid the waste of channel resources. Therefore, the probability detection CSMA with monitoring for WSNs MAC protocol has a better performance in the WLAN
