Abstract: Based on polling mechanism and random delay, a MAC protocol for EH-WSNs is proposed, that is, probabilistic polling for delay detection. The number of sensor nodes that have enough energy to upload data is confirmed through a polling cycle for receiving short detection packets, and the corresponding nodes are polled in the subsequent polling process. The network performance is maximized and the network efficiency is improved. The simulation results show that compared with other polling protocols, the delay detection probabilistic polling has higher throughput, better fairness and shorter arrival interval time.