Through the tests of three indexes， Brookfield viscosity， frequency scanning， linear amplitude scanning and dielectric constant of 90 ^# base asphalt and styrene-butadiene-styrene block copolymer （SBS） modified asphalt before and after thermal-oxidative aging， the changes of asphalt basic indexes， rheological indexes， fatigue properties and asphalt components before and after aging were studied. Moreover， the changes of indexes after short-term and long-term aging were quantified and the quantitative relationship between components and performance indexes was established. The results show that penetration is the most reasonable one among three indexes to describe asphalt aging degree. The viscosity， temperature sensitivity， complex modulus modulus master curve and fatigue resistance of base asphalt are much affected by thermal-oxidative aging than that of SBS modified asphalt. The viscosity and its temperature sensitivity of base asphalt change much obviously during short-term aging， while SBS modified asphalt change much obviously during long-term aging. The attenuation of fatigue resistance and complex shear modulus of the two asphalts mainly occurs in the long-term aging. It is feasible to use the permittivity to divide the asphalt components and correlate the performance changes of asphalt before and after aging.