The invention discloses an outsole sizing material for a pair of protective boots. Raw materials of the outsole sizing material comprise chloroprene rubber, butadiene-acrylonitrile rubber, styrene-butadiene rubber, a composite accelerator, organic montmorillonite, N-methylene carboxyl-2-benzothiazole sulfenamide, sulphur, high aromatic hydrocarbon oil, ethylene thiourea, mica powder, low-temperature calcined kaolin, diethylene glycol, an anti-aging agent, a liquid ethylene-propylene-terpolymer and a flame retardant. All the components are synergistic, compatibility is good, interface bonding strength is strong, insulating effect is excellent, flame retardant property is excellent, and high-low temperature resistance and waterproof and antiskid properties are relatively good, acid and alkali resistance, oil resistance and corrosion resistance are greatly improved, heat insulating property and permeability are strong, so that the outsole sizing material is soft, wear-resistant and nondeformable and also has comfort and strong generality under the premise that functional requirements are met.