Abstract: Subsea power line communication, as one of the main communication methods of subsea control system has a direct influence on the safety and cost of the subsea oil and gas exploitation. Umbilical cable power line is the carrier of subsea power line communication, of which the analysis on characteristics plays a vital role. As for a 30 km umbilical cable power line, state space model is established with the lumped parameter method, and the rlgc (resistance, inductance, conductivity, and capacitance) measured data of a subsea gas field is introduced into the system. The electrical characteristics of power line are researched further using the MATLAB software, and the selection principle of section number for π model is determined. The result of this study has a certain reference value for the channel design of subsea power line communication.