High-voltage direct current electrical method can effectively detect the integrity of landfill liner. The total loop current plays a decisive role in detecting result. Direct Current Circuit model for landfill leakage detection of high-voltage direct current method is established in this paper. The circuit is made up of four parts: grounding resistance of the power electrode in the medium above the liner, resistances of leaks in the liner, resistance of the liner and resistance of the soil under the liner. All parts of resistance are analyzed. The results show that: (1) the grounding resistance of power electrode is determined by medium resistivity, radius and the buried depth of the electrode; (2) the resistance of liner is proportional to the liner thickness and the material resistivity, but inversely proportional to the liner area; (3) the resistance of a leak can be modeled as the sum of the contact resistance with the material above the leak, the resistance of the material in the leak and the contact resistance with the material below the leak, among which the contact resistances are the main part; (4) the power electrodes should be buried deeply as far as possible and be poured with water in the surrounding soil to reduce the grounding resistance.