Abstract: The category of grounding system of 660MW ultra supercritical thermal power plant was introduced. Several important problems related with the grounding system of thermal power plant were expounded. Based on this, the protection of the grounding system was discussed emphatically, so as to find the more economical and more practical protection method of the grounding system.

Key words: grounding system of power plant, selection of protection method, corrosion mechanism, reason of corrosion, protection method