Abstract: In order to study the effect of aging on microstructure and fatigue properties of modified asphalt, the asphalt routine index test, the Dynamic Shear Rheometer(DSR) test and the AFM test were used to analyse penetration, ductility, softening point, fatigue performance and microstructure of styrene-butadiene-styrene tri-block copolymer(SBS) modified asphalt and rubber powder modified asphalt from the macro and micro perspective before and after aging.The results show that with the deepening of aging, the hardness of modified asphalt increases and the high temperature performance also improves, whlie the temperature sensitivity becomes lower and the low temperature crack resistance becomes worse. The anti-aging properties of rubber modified asphalt are better than that of SBS modified asphalt according to the comprehensive analysis of penetration ratio, ductility ratio and softening point ratio.With the decrease of temperature, the increase of frequency and the deepening of aging, the anti-fatigue performance of two modified asphalt is deteriorated. The microstructure observation results show that SBS modified asphalt has "bee-like structure" and the volume and height of "bee-like structure" increase after aging, but their numbers decrease.There is no "bee-like structure" in the rubber powder modified asphalt, it is due to some reactions like swelling, desulfurization and degradation occured in the blending process of asphalt and rubber powder that restricted the "bee-like structure" formation, and few changes occur in the roughness and the height of rubber powder modified asphalt surface after aging. Rubber powder modified asphalt has better fatigue resistance, aging resistance and high temperature performance than that of SBS modified asphalt.