In this paper, the secular changes of buried grounding electrodes was investigated; the electrodes are such facilities as grounding grid, grounding connector, grounding terminal and grounding rod etc.. The corrosiveness of removed substation grounding electrodes after commercial operation more than 50 years was measured and its conductivity deterioration trend was analyzed. The measuring results using three experimental methods were compared, finally the consideration for safe and economic grounding design were shown. As the result, it shows the maintenance necessity of grounding systems.