Abstract: The cathodic protection on bottom plates of large-scale aboveground storage tank is the critical technology thatdetermines service life of the storage tank. Various cathodic protection techniques for the bottom plates, anode placementmanners and flow characteristics of protective current are described. It is pointed out that the cathodic protection techniqueusing a flexible anode is the preferred solution for the design of cathodic protection system to a newly-built storage tankand renovation of cathodic protection system for an old tank's bottom plates. Currently, the major factors influencingthe maintenance of a cathodic protection system include stability, accuracy and positional arrangement of the referenceelectrode. Based on the practice of design and renovation of cathodic protection system for a 45 m diameter tank, it issuggested that for the exposed oversized bottom, cathodic protection system cost can be reduced significantly by providingimproved design for cathodic protection system for a large-scale tank.