Grounding grid is the important parts in power system to maintain the security of power system, electrical staff and equipment. How to effectively detect the abnormal condition of grounding grid is closely related to the secure and stale operation of power system. The Electromagnetic Tomography (EMT) technology is introduced in the paper to detect the abnormal condition of grounding grid conductors. Based to the result of induction voltage resulted from the EMT technology test system, the improved Landweber iteration algorithm is applied to obtain the reconstruction image of grounding grid conductors. The image correlation coefficient is defined to detect the abnormal condition of grounding grid conductors. The results of a 35kV substation grounding grid conductors under normal and typical faults including corrosion and fracture have shown that it is feasible to detect the abnormal condition of grounding grid conductors by the EMT technology with the advantage of non-contact and high sensitivity to the condition of grounding grid conductors. The defined image correlation coefficient is capable of recognize the abnormal condition of grounding grid conductors. The results could provide the important reference for the condition assessment of grounding grid.