The　identification　of　styrene-butadiene-styrene　(SBS)　content　is　crucial　in　engineering　applications　since　the　key　to　assessing　the　performance　of　aged-modified　asphalt　is　the　SBS　content.　Six　types　of　modified　asphalts　with　various　SBS　contents　were　prepared,　and　physical,　rheological,　and　Fourier-transform　infrared　spectroscopy　(FTIR)　tests　were　conducted.　The　fitting　relationship　between　aged-modified　asphalt　indexes　and　SBS　content　was　established,　and　the　three　methods＇　accuracy,　simplicity,　and　efficiency　were　compared　and　analyzed.　The　results　showed　that　the　fitting　relationship　between　SBS　content　and　viscosity　could　exceed　0.83　after　aging.　However,　the　linear　and　quadratic　fittings　deviated　from　the　measured　values,　and　the　softening　point　had　no　apparent　law　with　the　SBS　content.　The　rheological　index　method　significantly　correlated　with　SBS　content　and　is　highly　automated.　However,　FTIR　was　established　based　on　the　direct　detection　of　SBS　characteristic　peaks　compared　with　the　physical　and　rheological　indexes　methods.　It　could　directly　reflect　the　SBS　content　and　was　not　easily　disturbed　by　SBS　substitutes.　In　addition,　after　long-term　aging,　the　linear　relationship　between　SBS　characteristic　peak　index,　A(966)/A(811),　and　SBS　content　could　exceed　0.97.　The　FTIR　test　exhibited　high　accuracy　and　fast　detection　speed　and　is　the　best　detection　method　for　SBS　content.