In order to study the rheological and fatigue properties of polyphosphoric acid (PPA) modified asphalt, dynamic shear rheometer (DSR) was used to carry out temperature-sweep and time-sweep tests, and the relationship between complex shear modulus (G^*) and rutting factor (G^*/sin δ) of PPA modified asphalt with different content with temperature and loading time was analyzed. The loading times when the G^* decreases to 50% of the initial value (G0^*) were used to characterize the fatigue performance of PPA modified asphalt. The results show that the G^* and G^*/sin δ of asphalt decrease with the increase of temperature, namely, the higher the temperature, the worse the shear deformation resistance and high temperature stability of asphalt. When the temperature exceeds 60℃, the continuous increase of temperature has no effect on them. The PPA modifier could significantly improve the shear deformation resistance and high temperature stability of asphalt. The G^* and G^*/sin δ of 2.0% PPA modified asphalt are 2.5 times that of 70# base asphalt. Moreover, the higher the PPA content, the longer the fatigue life of modified asphalt and the better the fatigue resistance of asphalt. The fatigue life of PPA modified asphalt has a significant linear decreasing relationship with loading stress in double logarithmic coordinates, and the linear goodness of fit R² is greater than 0.9. In addition, PPA modifier can improve the shear deformation resistance and elastic recovery ability of asphalt, especially when the loading frequency is low.