Abstract: Based on the fractional viscoelastic model, the effects of RH or Evotherm warm-mixed agent on the low-temperature properties of styrene-butaniene-styrene block copolymer(SBS) modified asphalt were analyzed by low temperature bending beam rheometer test (BBR).The results show that the parameters of fractional viscoelastic model fitted with BBR test data can be used to predict the creep compliance and creep rate of the modified asphalt; RH warm-mixed agent can improve the damping ratio and the dissipation energy ratio of the SBS modified asphalt, while Evotherm warm-mixed agent can not improve them at below -18℃; Because the seven kinds of asphalt are the same order in accordance with the damping ratio and dissipation energy, the damping ratio can be used as an evaluation index of low-temperature properties of warm-mixed modified asphalt; RH can improve the creep compliance of asphalt and viscous flow compliance, the greater the dosage, the better the improvement, but it can't improve the viscoelastic ratio, so the viscous ratio can't be used to evaluate the low-temperature properties of warm-mixed modified asphalt and the regularity of Evotherm warm-mixed agent is not strong; the low-temperature properties of SBS modified asphalt are poorly improved at below -24℃ using the two kinds of warm-mixed agents.