Abstract:The low temperature performance of different original asphalts, polyphosphoric acid(PPA) modified asphalt and composite modified asphalts based on PPA(PPA+SBS, TB+PPA+SBS) were investigated by ductility test(5℃), penetration test(25℃) and bending beam rheometer(BBR). The results show that the low temperature performance of the Esso 70# asphalt is improved while the low temperature performance of Iran 70# asphalt declined with the increase of the amount of PPA which indicated that the modification effect of PPA modified asphalt is related to the chemical composition of original asphalt. Based on the PG index, the low temperature performance of PPA+SBS increases first and then decreases and from the 5℃ ductility value, the increase of PPA on the low temperature performance of PPA+SBS is unfavorable. The softening point value indicates that PPA could improve the high temperature performance of TB+PPA+SBS. Overall, the influence of PPA on the low temperature performance of TB+PPA+SBS and PPA+SBS is not obvious and the performance of asphalt binder is mainly determined by TB rubber powder and SBS, TB rubber powder can significantly enhance the low temperature performance of asphalt binders.