To prepare high-viscosity asphalt for drainage asphalt pavement in China, the effect of TPS contents and kinds of base asphalt on the properties of modified asphalt was investigated by tests in laboratory. The 60 ℃ dynamic viscosity is an important parameter for high-viscosity modified asphalt. The results indicate that strong correlations exist between the chemical composition of base asphalt and the properties of TPS modified asphalt. The viscosity of modified asphalt at 60 ℃ increases with the increasing of asphaltine content of base asphalt at same contents of TPS. When the TPS content is between 14％-16％, it has significant influence on viscosity of modified asphalt at 60 ℃, the viscosity increases rapidly, and can reach to specifications for high-viscosity modified asphalt. The temperature sensibility of the asphalt modified by TPS is decreased obviously, and the high-temperature stability, cracking resistance at low temperature and elastic recovery are all increased.