The invention provides a large-mixing-amount steel slag powder grinding aid increasing hydration speed, prepared from the following components by weight: 30 to 31 parts of water, 5 to 7 parts of industrial salt, 3 to 5 parts of anhydrous sodium sulphate, 2 to 4 parts of sodium thiosulfate, 3 to 5 parts of sodium nitrite, 5 to 7 parts of urea, 1 to 3 parts of lignosulfonic acid, 7 to 9 parts of triethanolamine, 14 to 16 parts of complex alcohol amine, 13 to 17 parts of glycerin, and 6 to 7 parts of sugar. The large-mixing-amount steel slag powder grinding aid has good adaptability, improves thecement strength at various ages, reduces the use amount, saves energy, and protects the environment.