Abstract: Because of the random fading and noise, there exists the low-reliable problem in power line communication system. To solve the low-reliable problem, the concept of equivalent link is proposed, which convey the multiple-hop link quality to virtual single-hop link quality, to evaluate the performance of the power line communication network topology. Based on this, an optimization method for layered network topology is proposed. Using this topology, the high-reliable node can be easily found and chosen as relay to improve the reliability.