The invention discloses a gas-shielded overlaying flux cored soldering wire for repairing a hot-forging mould, which is manufactured by taking SPCC-SD cold-rolling low-carbon steel belts as raw materials of a soldering wire and utilizing a conventional flux cored transient alloy way, a universal flux cored standard and a flux cored soldering wire manufacturing technique. The soldering wire flux core contains fluoride, calcium carbonate, feldspar, magnesia and alloy powder according to a proportion, wherein the fluoride comprises calcium fluoride, sodium fluoride and barium fluoride, and the alloy powder contains iron powder, high-carbon ferrochrome, electrolytic manganese, ferrosilicon, ferromolybdenum, ferrovanadium, nickel powder, tungsten powder and cobalt powder. The invention has the following beneficial effects: because the gas-shielded overlaying flux cored soldering wire takes CO2 or a gas mixture with volume percentage ratio of 80% Ar and 20% CO2 as the protective gas, the gas-shielded overlaying flux cored soldering wire has the advantages of great soldering technique, stable electric arc, less splash, easy deslagging, good crack resistance, great high-temperature hardness and thermal fatigue resistance, continuous soldering and improvement on production efficiency.