An equivalent circuit model is put forward through analysis of the experiment data under the conditions of applying 400V, 350V and 300V DC supply power to a small-scale simulated landfill. Due to the fact that the existence of the HDPE geomembrane liner endows the model with commutating character, the electrolytic capacity increases as the area of geomembrane liner and the supplying electric voltage increase. The contact electric resistance of the power supply electrode is in direct proportion to earth electric resistance rate, and in relation to the diameter of the electrode and the depth of the earth. Moreover, the contact resistance is mainly determined by the earth electric resistance around the electrode (the influence induced by the earth farther than 10 times electrode radius is less than 10 percent of those involved by all resistance), hence decrease of the earth electric resistance rate around the electrode may result in effective decrease of the contact electric resistance of the electrode.