Through penetration， softening point， ductility， four components test and dynamic shear rheological（DSR） test， the high temperature rheological properties of polyphosphoric acid（PPA） modified asphalt binders were studied and compared with the matrix asphalt and SBS modified asphalt binder. The results show that the addition of PPA can improve asphalt high temperature rheological properties significantly. With the increase of PPA content， softening point improves， penetration decreases， complex shear modulus increases， phase angle decreases， and rutting factor increases for PPA modified asphalt binders， indicating that asphalt high temperature properties improve with the addition of PPA. DSR tests indicate that the high temperature properties of modified asphalt binder with 1.0%(by mass) PPA equals to that with 4.0% SBS . Almost every 0.5% increase of PPA content makes the high temperature PG level raise a level. The addition of PPA has obvious influence on the asphalt binder component， the content of asphalt is notably increased， the gum content is significantly reduced， and the high temperature resistance to permanent deformation of asphalt binder can be improved by using PPA.