Abstract: Based on the heat fluid energy equation and the cathodic protection mathematics model controlling e-quation, the tank bottom cathodic protection mathem-atics model of the deepwell anode is established. Considering the asymmetry of the soil medium, imposing the two classical current density hypothesis, the protective potential is obtained, get to the conclusion that abstract: (1)the two protective potential laws are resemble; (2)The biggest difference of the tank bottom protective potential lies in horizontal axes, for the single tank and single deepwell anode, the minimum of protective potential lies in the certain point of horizontal axes, not the center of the tank; (3) the vertical potential asymmetry is larger than that of the horizontal and diagonal; (4)lying in a critical anode depth, the influence of the depth to the intimate region is larger than that of the center and distance region. Employing the method, the case of the multi-tanks and multi-deep-well anodes can be studied in order to accurately calculate the difference of the tank bottom protective potential.