Aiming at the hidden node and exposed node problem caused by asymmetry transmit power in wireless sensor
networks(WSNs), an MAC protocol for power control(MAC4PC) is proposed, which adopts a neighbor vector to record the status of neighbor nodes and the information of current conservations. Furthermore, a time schedule of the control frames and an interference degree criterion are designed to ensure the feasibility of parallel transmission in this protocol. Simulation results show that, in comparison with 802.11 DCF, SB-FSMA /CA and GLPCB-PMAC, MAC4 PC protocol not only improves the average network throughput, but also reduces the average energy consumption and the average delivery delay.