In recent years, power line communication technology has seen a rapid development. However, due to the unsteadiness of the power line channels, the communication attenuation and bit error rate is still a big problem. Based on the previous research of spread spectrum communication and orthogonal frequency division multiplexing (OFDM), in this paper, we studies the method to eliminate attenuation using OFDM in low voltage power line communication, and gives the system model based on transmission characteristics. We also studies the way to improve the accuracy of signal transmission and reduce the bit error rate by changing the guard interval and error-correcting schemes. At the same time, the result of test and simulation is given. The alternative scheme provides a significant performance in anti-interference ability and considerable computational complexity reduction compared to the usual scheme.