The anti-corrosion of the steel gate of Three Gorges dam navigation lock is the major factor that impacts the time spent on the check and maintenance of navigation lock.The corrosion of the steel gate is mainly electro-chemical corrosion.This paper analyzes the mechanism and the advantages & disadvantages of cathodic protection and coating anti-corrosion techniques,and comes to the conclusion that the best anti-corrosion method,which answers to all demands,is the combination of both cathodic protection technique and coating technique.