为明确不同相对分子质量的星型与线型苯乙烯-丁二烯-苯乙烯嵌段共聚物（styrene butadiene styrene block polymer, SBS）对基质沥青改性后性能的影响，通过内掺法（5%掺量）制备不同相对分子质量的改性沥青。结果表明：SBS的添加对于提高沥青性能具有明显的促进作用，主要是针入度、软化点和延度3项关键指标的提升，以及高温流变性能的增强。同时，不同相对分子质量的SBS对改性沥青的性能提升存在差异，一定范围内，相对分子质量更高的SBS表现出更好的性能提升效果。可见，针对不同需求的道路工程，选择合适的SBS相对分子质量对于优化沥青材料性能，提高道路工程的质量和耐久性具有重要指导意义。

In order to clarify the effect of star and linear styrene butadiene styrene block polymer (SBS) with different relative molecular weights on the performance of modified asphalt, modified asphalt with different relative molecular weights was prepared by internal blending method (5% content). The results show that the addition of SBS has a significant promotional effect on improving the performance of asphalt, which is mainly marked by the improvement of three key indicators such as penetration, softening point and ductility, as well as the improvement of high temperature rheological performance. At the same time, there are differences in the performance improvement of modified asphalt by SBS with different relative molecular weights. Within a certain range, SBS with a higher relative molecular weight exhibits better performance improvement effect. It can be seen that for road projects with different needs, choosing the appropriate SBS relative molecular weight has important guiding significance for optimizing the performance of asphalt materials and improving the quality and durability of road projects.