Abstract: The microstructure and the high-and-low temperature performance of matrix asphalt and styrene-butadiene-styrene tri-block copolymer(SBS) modified asphalt before and after the salt freezing cycle were studied by the AFM, DSR and BBR, respectively. The results indicate that the asphaltene content of matrix asphalt increases and the dispersion situation of matrix asphalt gets worse, and three-dimensional network structure of SBS modifier is destroyed due to the number and size of asphalt "bee" structures changing after freeze-thaw cycles. The high temperature performance of matrix asphalt increases slightly and anti-fatigue performance decreases after the salt freezing cycle, while high temperature property of SBS modified asphalt decreases and the fatigue properties increases. To a certain degree, the increase of salt concentration make the low temperature cracking resistance of matrix asphalt reduce. However, when the concentration of salt reaches up to 4wt%, the low temperature cracking resistance of SBS modified asphalt is improved. Hence, the high-and-low temperature performance of SBS modified asphalt is better than that of matrix asphalt. It is recommended that SBS modified asphalt should be chose as the pavement material in the cold region as far as possible.