Styrene-butadiene-styrene　block　copolymer　(SBS)-and　styrene-butadiene　rubber　(SBR)-compound　modified　asphalts　with　good　storage　stability　and　high-　or　low-temperature　properties　before　and　after　short-　and　long-term　ageing　are　prepared　by　the　addition　of　polyphosphoric　acid　or　sulfur　selectively.　The　effect　of　PPA　and　sulfur　on　the　storage　stability,　the　physical　and　rheological　properties　of　SBS-　and　SBR-modified　asphalts　before　and　after　ageing　is　studied.　To　improve　the　storage　stability,　high-　or　low-temperature　properties　of　SBS-　and　SBR-modified　asphalts　before　and　after　ageing,　the　SBR-modified　asphalt　should　be　modified　further　only　by　the　addition　of　PPA,　the　linelike　SBS-modified　asphalt　should　be　improved　by　the　addition　of　PPA　and　sulfur,　the　starlike　SBS-modified　asphalt　should　be　improved　only　by　the　addition　of　sulfur.　The　modification　mechanism　of　PPA　and　sulfur　in　the　preparation　of　those　polymer　modified　asphalts　(PMAs)　is　studied　further.　©　2013　Elsevier　Ltd.　All　rights　reserved.