Buton　rock　asphalt　(BRA)　is　possessed　of　both　performance　and　economic　advantages.　In　order　to　reveal　the　modification　mechanism,　X-ray　diffraction　experiment　(XRD),　X-ray　fluorescence　spectrum　analysis　and　environmental　scanning　electron　microscopy　experiment　(ESEM)　are　used　to　study　on　microstructure　of　BRA　in　this　paper.　It　demonstrates　that　BRA　can　extremely　adsorb　free　bitumen　due　to　abundant　microscopic　pores,　which　consists　of　70∼80　percent　Buton　rock　(BR)　minerals　and　20∼30　percent　pure　rock　asphalt　(RA).　RA　with　high　viscosity　is　strongly　adsorbed　internal　and　outer　of　the　surface　of　BR,　which　has　high　alkaline　pH,　high　crystallization　and　strong　surface　activity.　Then　a　special　microstructure　named　＇RA∼BR＇　blend　with　stable　property　and　strong　spalling-resistance　capability　develops.　Meanwhile,　dynamic　stability　rheology　test　(DSR)　is　employed　to　study　on　the　rheological　mechanics　property　of　BRA　modified　asphalt　mastic.　The　high　temperature　performance　grade　(PG)　level　of　BRA　modified　asphalt　mastic　with　different　mixing　content　is　determined.　The　reasonable　mixing　content　of　BRA　in　matrix　asphalt　is　20∼30　percent.　The　research　proves　that　BRA　modified　asphalt　possesses　wonderful　high　temperature　stability　and　has　broad　prospects　for　pavement　application.　©　(2011)　Trans　Tech　Publications.