The invention discloses a traffic anti-rut asphalt modifier and a preparation method thereof; the asphalt modifier is prepared from the following components in parts by weight: 20 to 200 parts of thermoplastic elastomer, 5 to 450 parts of polyolefin, and 5 to 400 parts of rubber powder. Simultaneously, the invention also discloses modified asphalt which contains the asphalt modifier and application of the modified asphalt in asphalt mixture. The invention can significantly improve the high-temperature performance and the anti-rut capability of the asphalt mixture, improves anti-water damage and anti-low temperature cracking and other performance, and has high cost performance. Compared with asphalt modification, the invention does not need to add asphalt modification equipment, can significantly reduce energy consumption and loss in the production process, can realize long-termed inventory, prevents the problem of the poor storage stability of modified asphalt, does not affect the mixing proportion design, does not change the gradation of the asphalt mixture under any content, only finely adjusts the asphalt-aggregate ratio, has simple construction process, and realizes random adding through a direct feeding method.