The invention provides a reactive type asphalt mixture additive, which comprises a component A and a component B, wherein the component A is a mixture of a first monomer and a second monomer, and the component B is a mixture of a diluting agent, a catalyst and a polymerization inhibitor. Based on the total mass of the reactive type asphalt mixture additive, the reactive type asphalt mixture additive comprises the following components in percentage by mass: 50-90% of first monomer, 0-30% of second monomer, 5-20% of diluting agent in the component B, 0.05%-1% of catalyst in the component B, and 1-10% of polymerization inhibitor in the component B. The reactive type asphalt mixture additive is low in viscosity, good in mobility, easily dispersed in the mixture, and short in curing time; and the high-modulus asphalt mixture prepared by adding the reactive type asphalt mixture additive is excellent in performance.