This paper presents a new wireless sensor network MAC protocol: the probability detection CSMA protocol with monitoring function based on the improved binary tree conflict resolution algorithm. By using the average cycle method, the paper gets the mathematical expressions of the throughput, system average delay of the probability detection CSMA protocol with monitoring function and the probability detection CSMA protocol with monitoring function based on the improved binary tree conflict resolution algorithm through complicated mathematical modeling, rigorous mathematical derivation. The computer simulation results not only confirm the correctness of the theoretical analysis but also show that the probability detection CSMA protocol with monitoring function based on the improved binary tree conflict resolution algorithm due to adding to the conflict resolution algorithm, resulting in the increases of systemic throughput but increase the time delay of the system.