The invention discloses a high modulus asphalt modifier and a preparation method and application thereof. The high modulus asphalt modifier is made of raw materials of 100 parts of polymer resin, 40-60 parts of ceryl polymer, 5-20 parts of bulking agent, 2-8 parts of grafting agent, 2-6 parts of ultraviolet light screening agent and 10-50 parts of padding. The polymer resin is the mixture of low density polyethylene and linear low density polyethylene in any proportion, and the parts are parts by weight. The high modulus asphalt modifier solves the problem that the existing anti-rut agents and high modulus asphalt annexing agents are difficult in feed, difficult to melt, poor in plasticizing, over-high in blending temperature and the like, simultaneously improves asphalt softening points, reduces viscosity of asphalt, improves anti-rut performance, low-temperature performance, anti-shearing performance and performance stability of an asphalt road face, and is simple in preparation and low in cost.