The invention provides a composite modified high-toughness asphalt mixture. The mixture is prepared from the following materials: matrix asphalt, styrene butadiene rubber, ethylene-vinyl acetate copolymer resin, an accelerant, extender oil, a crosslinking agent and organic amine, wherein the content of styrene in styrene butadiene rubber is 30-40wt%, and the number-average molecular weight of styrene butadiene rubber is 100000-120000 g/mol. According to the scheme, the influence on the elasticity of the asphalt mixture by the content of styrene in styrene butadiene rubber and the number-average molecular weight of styrene butadiene rubber is researched. The modified asphalt mixture manufactured according to the invention presents excellent performance, has high-temperature stability, low-temperature crack resistance and high toughness, and also has excellent construction workability, thereby being suitable for road conditions in the severe stress states, such as roads with high heavyload and overload rates, long-steep slopes, urban road intersections, steel bridge pavement and the like.