AbstractWith the rapid growth of traffic demands, the use of liquid chemical material instead of traditional modifier to prepare high-performance modified asphalt demonstrates dual values in environmental protection and performance improvement of pavement. The objective of this study is to assess the efficiency and reveal the modification mechanism of using a developed polyurethane precursor–based reactive modifier (PRM) in the preparation of polyurethane precursor–modified asphalt. The selected petroleum asphalts (60/80 pen grade) were modified at 1.5%, 2.5%, and 4% by weight. Samples of the base asphalt and PMA binders were characterized by dynamic shear rheometer, time sweep fatigue test, and single-edge notched beam tests. The modification mechanism was finally demonstrated by the fraction analysis, Fourier transform infrared spectroscopy, differential scanning calorimeter, atomic force microscopy, and fluorescence microscope. Owing to the presence of polar groups in neat asphalt, the use of PRM can be treated as a chemical method for the modification and it shows good compatibility with neat asphalt. The incorporation of PRM to the asphalt matrix can notably improve the high-temperature performance and fatigue resistance of asphalt. In addition, the PMA presents desirable low-temperature crack resistance and aging resistance. Considering the relatively low level of preparation temperature (145°C) and the huge improvement in high-temperature performance, the modification using PRM can be regarded as an environmentally friendly alternative for the production of polymer-modified asphalt, especially in high-temperature regions.