The invention discloses a solder for exothermic welding of a grounding body in a grounding system and an ignition agent of the solder, relates to the solder for the exothermic welding and the ignition agent of the solder and solves the technical problem of poor welding performance caused by impurities contained in a welding joint which is obtained by the conventional exothermic welding hot-melting soldering agent. The solder for the exothermic welding of the grounding body in the grounding system consists of copper oxide powder, copper powder, industrial pure aluminum powder, zinc powder, zirconium powder, silicon iron powder, fluorite powder, marble powder and lanthanum cerium alloy powder. The ignition agent of the solder for the exothermic welding of the grounding body in the groundingsystem consists of magnesium powder, the copper oxide powder, the industrial pure aluminum powder, potassium permanganate powder and red phosphorus powder. When the solder and the ignition agent are used, the mass ratio of the solder for the exothermic welding of the grounding body in the grounding system to the ignition agent is (78-82):1. All elements in the solder and rare-earth elements can purify the welding joint. The invention is applicable to welding of copper, copper alloy, steel, galvanized steel, copper-clad steel, stainless steel and high-resistance heating source materials.