In order to explore the effect of aging on the temperature stability of styrene-butadiene-styrene (SBS)-modified asphalt, matrix asphalt and SBS-modified asphalt were used as the control to conduct short-term aging and long-term aging. Three indexes of asphalt with different aging degrees were tested to analyze the change rule of each index. The specific heat capacity and phase transition temperature of SBS-modified asphalt before and after aging were studied by differential scanning calorimetry (DSC). At last, the mechanism was studied by attenuated total reflection Fourier infrared spectroscopy. The results show that the penetration and ductility of matrix asphalt and SBS-modified asphalt decrease with the deepening of aging. The difference is that the softening point of matrix asphalt shows an increasing trend, whereas the softening point of SBS-modified asphalt shows a changing rule of first decreasing and then rising. The addition of SBS modifier can increase the specific heat capacity of asphalt and change the viscosity-flow conversion temperature. The degradation of SBS modifier leads to the decrease of the specific heat capacity after long-term aging, whereas the viscosity-flow conversion temperature decreases first and then rises, which is consistent with the change law of softening point. As a special block copolymer, the specific heat capacity of SBS modifier is determined by the polymer butadiene with lower glass transition temperature, whereas the softening point changes with the polymer styrene with higher glass transition temperature, which is consistent with the change rule of functional group index, softening point, and specific heat capacity of SBS-modified asphalt before and after aging.