The invention discloses a high-weather-resistance fireproof steel welding alkaline flux-cored wire. Flux-cored wire powder comprises components including, by weight percent, 18%-35% of magnesia, 5%-20% of fluorite, 3%-8% of barium fluoride, 6%-13% of zircon sand, 1%-7% of manganese ore, 5%-12% of rutile, 2%-5% of marble, 1%-3% of an aluminum-magnesium alloy, 0%-2% of sodium fluosilicate, 0%-1% oflithium fluoride, 0%-1% of lithium carbonate, 2%-5% of high carbon ferro-chrome, 0%-12% of micro-carbon ferro chrome, 0.3%-4% of copper powder, 0.2%-16% of nickel powder, 1.5%-4% of silicon iron, 1.8%-8% of manganese powder, 1.6%-5% of molybdenum powder, 1%-3% of ferrotitanium, 0.1%-1% of ferroboron, 0%-0.5% of ferroniobium, 0%-0.8% of ferrovanadium, 0%-2% of tungsten powder, 0.2%-3.2% of rare earth oxide, 0%-1% of graphite and the balance iron powder.