The　linear　amplitude　sweep　(LAS)　test　has　been　widely　accepted　for　estimating　the　fatigue　resistance　of　asphalt　binders　in　the　last　10　years.　This　paper　proposes　a　fracture　mechanics-based　analytical　approach　for　crack　initiation　and　propagation　characterization　in　the　LAS　test,　aiming　to　more　precisely　explore　the　binder　crack　growth　and　failure　mechanism.　Seven　unmodified　neat　asphalt　binders　and　one　styrene-butadiene-styrene　(SBS)　polymer-modified　binder　are　selected　in　this　study.　The　crack　length　(a),　rate　of　cracking　(da/dN),　stress　intensity　factor　(K),　and　energy　release　rate　(G)　are　the　fundamental　parameters　for　the　data　interpretation　approach　proposed　in　this　paper.　Experimental　and　analysis　results　demonstrate　that　the　energy-based　failure　definition　(either　from　continuum　damage　mechanics　or　fracture　mechanics)　should　be　utilized　to　detect　the　material-dependent　failure　occurrence　in　LAS　test.　The　fracture　behavior　of　asphalt　binder　in　the　LAS　test　follows　the　two-phase　crack　growth　(TPCG)　model　in　terms　of　the　crack　initiation　and　crack　propagation.　The　crack　propagation　phase　further　consists　of　stable　crack　growth　and　unstable　crack　growth.　It　is　found　that　the　fatigue　performance　of　asphalt　binder　is　intrinsically　governed　and　dominated　by　its　resistance　to　the　crack　propagation.　The　SBS　binder　in　this　study　clearly　displays　slower　crack　propagation　behavior　than　other　neat　binders.　Additionally,　the　traditional　fatigue　life　can　also　be　divided　into　the　crack　initiation　life　and　crack　propagation　life,　which　is　promising　to　clarify　the　specific　modification　contribution　to　binder　fatigue　resistance.　The　two　critical　crack　lengths　of　initiated　crack　and　propagated　crack　for　a　given　asphalt　binder　are　found　to　be　correlated　to　each　other,　indicating　the　potential　links　between　the　binder　crack　initiation　and　propagation　behaviors.　(c)　2020　American　Society　of　Civil　Engineers.