The PS-MMT was synthesized through intercalating styrene monomer into the layer of MMT by in-situ polymerization. Composite modified asphalts with PS-MMT and SBS were prepared by melt blending. Rolling thin film oven test (RTFOT) was carried out to study the aging property. The results demonstrate that both modified MMT and SBS homogeneously disperse in the base asphalt, which lead to an improvement in terms of toughness, strength, and thermal stability. Impact of the PS-MMT on the properties of SBS modified asphalt appears as a decreasing penetration, an increasing softening point, and a decreasing ductility. Compared with that of SBS modified asphalt, the anti-aging property of PS-MMT /SBS modified asphalt was greatly improved.