Abstract: In order to improve the compatibility of SBS（styrene-butadiene-styrene block copolymer） polymer and base asphalt, give full play to the modified effect of SBS and further improve the high-temperature and anti-aging properties of SBS modified asphalt, nano CaCO₃ was chosen to modify SBS modified asphalt. The effects of different amount of nano CaCO₃ on physical properties, high temperature rheological properties, low temperature rheological properties and anti-aging properties of SBS modified asphalt were analyzed through three indexes tests, multiple stress creep recovery test（MSCR）, bending beam rheometer test（BBR） and temperature scanning test（TS）. Considering the effect of nano CaCO₃ on the performance of SBS modified asphalt, the reasonable content of nano CaCO₃ was recommended. The compatibility of SBS modified asphalt and nano composite modified asphalt was compared and analyzed by segregation test. Through rutting test, trabecular bending test, immersion Marshall test and freeze-thaw splitting test, the high-temperature stability, low-temperature crack resistance and water stability of nano composite modified asphalt mixture were studied. The results showed that, nano CaCO₃ can improve the high-temperature and anti-aging properties of SBS modified asphalt. Considering the effect of performance impact comprehensively, it was suggested that the reasonable content of nano CaCO₃ in composite modified asphalt was 4%. Nano CaCO₃ can effectively improve the compatibility between SBS and asphalt. Compared with SBS modified asphalt mixture, nano composite modified asphalt mixture had better high-temperature stability and slightly improved water stability. The results showed that the comprehensive performance of nano CaCO₃/SBS composite modified asphalt and mixture was good, which was more suitable for application in hot areas in the South of China.