由于苯乙烯-丁二烯嵌段共聚物（styrene-butadiene-styrene block copolymer, SBS）改性沥青结构与性能之间的本构关系不明确，目前提高SBS改性沥青性能的方式仍是单纯提高其SBS含量，然而路面早期病害依旧频发。为了在不增加SBS含量情况下，探明SBS的溶胀程度对改性沥青流变性能的影响及其内在机理。采用荧光显微镜观察SBS改性沥青微观形貌，以动态剪切流变仪分析SBS改性沥青的常规性能与流变性能，利用分子动力学揭示SBS溶胀程度对其改性沥青性能影响的内在机理。结果表明：完全溶胀状态的星线共混型SBS改性沥青具有更高的溶胀面积，在常规性能，流变性能以及抗老化性能方面具有明显的性能优势。分子模拟则表明SBS的完全溶胀使得SBS改性沥青的径向分布函数峰更高，提升了SBS改性沥青中SBS分子与轻组分之间的交互作用，在保持了原有稳定沥青胶体结构的基础上使得SBS苯乙烯端相互连接，形成π-π共轭，提升了SBS网络的韧性。

Due to the unclear constitutive relationship between the structure and performance of styrene-butadiene-styrene block copolymer(SBS) modified asphalt, the current way to improve the performance of SBS modified asphalt is still to simply increase its SBS content. However, early pavement diseases are still frequent. To explore the effect of swelling degree of SBS on the rheological properties of modified asphalt and its internal mechanism without increasing SBS content. The microstructure of SBS modified asphalt was observed by fluorescence microscope. The conventional properties and rheological properties of SBS modified asphalt were analyzed by dynamic shear rheometer. The internal mechanism of the influence of SBS swelling degree on the performance of SBS modified asphalt was revealed by molecular dynamics. The results show that the fully swollen star-line blended SBS modified asphalt has a higher swelling area, and has obvious performance advantages in terms of conventional performance, rheological properties and anti-aging properties. Molecular simulation shows that the complete swelling of SBS makes the radial distribution function peak of SBS modified asphalt higher, which improves the interaction between SBS molecules and light components in SBS modified asphalt. On the basis of maintaining the original stable asphalt colloid structure, SBS styrene ends are interconnected to form π-π conjugate, which improves the toughness of SBS network.