As an important nature subject, electrochemistry is widely used in many fields. Hydrometallurgy is a new metallurgical technique which has a not clear mechanism of production technology. Electrochemistry has a wide use and important significance in the process flows of gold hydrometallurgy including grinding, mineral processing, pretreatment, et.al. The paper used electrochemical theory to discuss the mechanism in the production technology of gold hydrometallurgy including grinding, mineral processing, pretreatment, cyanide leaching, electrodeposition, slurry electrolysis, noble metal recovery, wastewater treatment, et.al. and explained the principle of the process flows in gold hydrometallurgy. Gold hydrometallurgy could be studied profoundly for these. Basing on explaining mechanism and representing principle, the application of electrochemical technique in the hydrometallurgy was also briefly introduced.