One of the most important problems in petroleum & gas liquids storage tank is bottom corrosion.Storage tank leakage will cause under ground water pollution & irreparable damages to environment. Early, storage tank's bottom (external part of tank that is connecting to earth) was protecting from corrosion by catholic protection. By the available experience , utilizing cathodic protection can stay leakage entirely and also it prevent storage tank bottom corrosion, this problem happen for a number of storage tank in Iran. this paper bring some reason about the cathodic protection system’s ability & also utilizing sacrifice Anodes on petroleum and gas liquids storage tank in order to protect & cover in corrosion Inhibitors.