The invention relates to a long-acting antiseptic resistance-reducing agent for protecting a grounding device to normally run. The resistance-reducing agent is formed by mixing 35-70 percent by weight of bentonite and 30-65 percent by weight of petroleum coke. The resistance-reducing agent has the advantages of higher viscosity, compact structure, less influence by climatic factor due to difficult loss along with rain water on the basis of sufficient permeability, long-acting performance, obvious resistance-reducing effect, good antiseptic effect, no toxic element and no pollution to the environment.