Attenuation of signal is one of the most important factors influencing power line communication’s reliability. In order to accurately analyze the high-frequency signal transmission in power line which is often affected by skin effect and dielectric effects, three-conductor power cable models which is made of RLCG circuit is proposed. The principle of RLCG model is analyzed in detail, and basis cell of RLCG parameters are deduced from the impedance measurement and identification of genetic algorithm. It models RVV 3G 2.5 mm2 power lines, and compares the simulation results with RLCG model and the measurement results. Experimental results show that RLCG model is validated in both time and frequency domains, which can provide the basis for the study of power line carrier communication systems.