A certain proportion of SBS, SBR, stabilizers and furfural extract oil was added in 90# base asphalt. After rolling thin film oven test and pressure aging test, the short term aging and long term aging asphalts were obtained. Changes of relative molecular mass and thermal properties of modified asphalts caused by temperature change were studied by gel permeation chromatography test, differential scanning calorimetry and thermogravimetric experiment. The results show that the structure of single addition SBR modified asphalt is the most unstable, and its anti aging property is the worst. Decomposition of macromolecules and polymerization of small molecules are suppressed during aging process of the stabilizer group and furfural extract oil group modified asphalt. Their temperature stability is improved. The mass loss of asphalt in the process of heating is mainly divided into three stages:less than 200℃，200420℃ and 420550℃. The reaction is strong in the third stage and the mass loss rate is the highest.