The conventional high temperature performance test and the Superpave high temperature performance test were carried out by using different modified asphalt binders,thus achieving different high temperature performance indexes.Then,the relationships between the indexes were discussed.Moreover,the high temperature performance of asphalt mixtures was verified by the improved rutting test,and the correlation between the high temperature performance of the asphalt binder and that of the asphalt mixture was investigated.Finally,the modification mechanisms of the polyphosphoric acid ( PPA) -modified asphalt and the SBS compound PPA-modified asphalt were analyzed by means of DSC.The results show that ( 1) the softening point and the accumulated strain can evaluate the high temperature performance of different types of asphalt binders more accurately; ( 2) the addition of PPA can decrease the heat flow rates of both the matrix asphalt and the SBS-modified asphalt,thus improving their thermal stability; and ( 3) the cumulative strain can be used as a reasonable evaluation index of high elastic modified asphalt binder.