The invention belongs to the field of traffic engineering admixtures, and relates to preparation and application of a high-modulus warm-mix asphalt additive. The additive is prepared mainly from a high modulus warm-mix main agent, a thermoplastic elastomer, vegetable oil, a crosslinking agent, a coupling agent, an antioxidant, an antiager and tackifying resin through single-screw low-temperature extrusion and granulation. The additive prepared can be direly added into a material mixture, and is suitable for high-modulus asphalt pavement engineering and winter low-temperature construction environments having high requirements on environment protection. An asphalt mixture prepared by utilizing the additive has excellent high-temperature performance, high dynamic modulus, good low-temperaturetoughness, excellent resistance to water damage, and the like, can reduce temperature for construction such as material mixture mixing, paving and grinding by 20-30 DEG C, achieves a warm mix effects, and is suitable for promotion and application.