The reliability of power line communication（PLC） is the most important factor that limits the application of PLC in practice. For the public network， the communication security of the low-voltage network has become an issue of growing concern. The advantages and the disadvantages of orthogonal frequency division multiplexing（OFDM） and chaotic frequency hopping（CFH） applied in PLC are discussed in the light of communication reliability and security， and the feasibility of the CFH-OFDM system that combines OFDM and CFH is briefly analyzed. A CFH-OFDM system is put forward and designed， which is applicable to high speed communication in low-voltage networks. The system introduces the CFH into the coding system of OFDM， which can improve the system performance of anti-jamming and the security of communication system. Simulation results show that the CFH-OFDM can improve the correcting ability and the reliability of PLC while providing a method for improving the information security of the low power line communication system.