Asphalt　binder　is　a　complex　compound　comprising　a　diverse　and　intricate　range　of　hydrocarbons　which　makes　it　difficult　to　accurately　ascertain　its　chemical　structure.　This　study　aimed　to　analyze　the　chemical　composition　of　asphalt　binder　and　establish　an　accurate　molecular　structure　model　of　unaged　asphalt　binder　fractions.　An　unaged　asphalt　binder　was　separated　into　four　fractions　based　on　their　polarities,　referred　to　as　saturates,　aromatics,　resins　and　asphaltenes　(SARA　fractionation).　A　combination　of　results　from　analytical　techniques　including　Fourier　transform　infrared　spectrometer,　1H-Nuclear　magnetic　resonance,　Gel　permeation　chromatography　and　Elemental　analysis　was　used　to　analyze　the　chemical　composition　of　the　different　fractions　of　asphalt　binder.　The　parameters　relating　to　the　average　molecular　structure　were　calculated　to　construct　an　average　molecular　structure　using　an　improved　Brown-Ladner　method.　The　results　show　that　the　improved　Brown-Ladner　method　can　be　used　to　obtain　the　effective　average　molecular　structure　of　the　SARA　fractions.　This　study　also　provides,　perhaps　for　the　first　time,　model　molecular　structures　for　each　polar　fraction　using　real　asphalt　binder　samples　that　can　be　used　in　future　studies　on　molecular　modeling　and　simulation.　The　average　molecular　structure　of　saturates　was　seen　to　be　relatively　simple.　However,　there　were　many　unsaturated　aromatic　compounds　and　polar　functional　groups　in　resins　and　asphaltenes.　The　presence　of　carbonyl　groups　in　resins　indicated　that　it　could　be　more　easily　aged　than　other　fractions.　The　average　molecular　weight　increased　from　several　hundred　to　nearly　two　thousand　with　an　increase　in　polarity　of　the　fraction　(saturates,　aromatics,　resins,　and　asphaltenes).　Similarly,　the　aromatic　carbon　ratio　increased　from　0.28　to　0.52,　and　the　cycloalkane　carbon　decreased　from　0.29　to　0.08　with　an　increase　in　polarity.