Abstract: after completion of tank construction, the change of grounding system will be out of peopleâs sight. The soil resistance will be changed and the metal component will be corroded by acid content in the soil and the grounding resistance will be gradually increased with the time passing by. We have carried out study of on-line monitoring system of grounding resistance to monitor the change of grounding resistance with the seasonal variation. The monitoring system is mainly composed of the grounding resistance acquisition sensor system, wireless or wired network data transmission system and online remote monitoring and recording system, and realized on-line monitoring function of oil tank.