Taking 110 kV single-core submarine cable as the research object, the transient thermal circuit model is established. Considering the loss of lead pack and armor, steady-state temperature formula of the conductor is calculated. It is envisaged that some resistor is stringed into the lead package armored loop, according to the actual production, in order to reduce the heating of submarine cable. The appropriate resistor is selected according to the cable design specifications and the actual situation of subject cable. The flow tests under different conditions are conducted on the subject cable based on the thermal cycling test system. Through the comparison and analysis of experimental data, it is proved that this method can effectively reduce the loss of the submarine cable and the steady-state temperature rise of conductor, thus it improves the current carrying capacity of the submarine cable.