Abstract: In viewing of the defects that exist in numerical simulation of deep well anode vs. tank bottom cathodic protection, a new method is presented for achieving protection potentials based on the assumption of typical distribution of current density. The calculation area consists of soil and asphaltic sand basement, and the physical model of cathodic protection system is used to approximately calculate polarization potential of deep well anode. Two cathodic protection programs are presented for oversize tanks (with a diameter of 80m). Their advantages and disadvantages are evaluated based on numerical calculation results. The cathodic protection methods for oversize tanks are also preliminarily discussed.