According to the requirements of power industry specifications on communication data of the distribution power grid（DPG），an enhanced quality of service（QoS）-media access control（MAC）model with channel access mechanism based on IEEE802.15.4protocol is researched.By dividing the three communication data of telesignalisation，telecontrol and telemetering in DPG into three priority levels of transmit data，a Markovian chain model of node buffers is built.According to the model，every nodes channel access conflict model，different priority levels of network data throughput models，the communication time-delay model and wireless channel collision model are developed.A simulation analysis is designed to analyze the wireless sensor networks（WSNs）data communication performance of the DPG.The simulation results in different distribution data rate scenarios show that the method proposed is able to provide effective QoS for DPG data communication based on WSNs.