The invention discloses a traffic anti-rutting asphalt modifier and a preparation method thereof, and the asphalt modifier is prepared by the following component in parts by weight: 10-20 parts of polyolefin, 1-80 parts of rubber powder and 0.5-1 part of antioxidant. The invention simultaneously discloses modified asphalt containing the asphalt modifier and an application of the modified asphalt in asphalt mixture. The invention can significantly improve the high-temperature performance and the anti-rutting capacity of the asphalt mixture, improve the resistance to water damage, the resistance to low temperature cracking and other performances and have high performance-price ratio. Compared with asphalt modification, the invention does not need to add an asphalt modification device and can significantly reduce the energy consumption and the loss during the production process, realize the long-term storage, avoid the problem of poor storage stability of the modified asphalt, not affect the design of the mixing proportion, not change the graduation of the asphalt mixture under any content and only need to carry out micro-adjustment on the asphalt-aggregate ratio; the construction process is simple; and the direct input method can realize the addition at will.