The invention relates to the technical field of modified asphalt preparation. The invention particularly relates to modified asphalt and a preparation method thereof. The modified asphalt is preparedfrom asphalt, benzofuran-indene resin, an acrylic acid-butadiene copolymer, hexamethylphosphoramide, dodecyl dimethyl benzyl ammonium chloride, triphenyl phosphate, decabromodiphenyl ethane, coco-glucoside, trihydroxyethyl isocyanurate, silica, white carbon black, magnesium mica, sodium metasilicate, zinc borate, attapulgite, an emulsifier, a filler, a dispersing agent, a compatilizer and a composite auxiliary agent. The asphalt, the benzofuran-indene resin and the acrylic acid-butadiene copolymer are subjected to chemical crosslinking, so that the asphalt, the benzofuran-indene resin and theacrylic acid-butadiene copolymer are connected through chemical bonds with relatively strong acting force to form a three-dimensional network-shaped spatial structure; the rut resistance of the asphalt can be obviously improved; anti-aging performance, weather-resistant performance and self-adhesion performance of the asphalt can also be obviously improved.