In order to verify the influence of different block proportions S /B on the effect of SBS modified asphalt， the dynamic mechanical performance test and static loading test were performed on the samples composed of different kinds of SBS with base asphalt. It is found that different S /B values fix on different modified effects and different viscoelastic mechanical behaviors， due to biphasic separate fabric of polybutadiene and polystyrene in SBS. In low-speed running pavement， the modified asphalt with lower S /B value shows better pavement performance， while in high-speed running pavement， the modified asphalt with higher S /B value shows better pavement performance. As far as SBS modified asphalt itself is concerned， mixing proportion impacts on resisting displacement and block proportion S /B ratio impacts on strain recovery capacity. In the case that the conditions are the same， SBS modified asphalt with different S /B values can be used for different travelling speed pavement construction demands to get an intelligent use.

       Key words: SBS modifier; block proportion; dynamic mechanical test; static loading test