The　phenomenon　of　cyclic　hardening　is　observed　in　fatigue　tests　of　modified　asphalt　controlled　by　low　strain/stress　level　and　it　is　not　clear　how　the　phenomenon　affects　the　fatigue　properties　of　binders.　The　special　time　weep　tests　were　performed　to　investigate　the　point.　Tests　results　indicate　that　the　cyclic　hardening　is　caused　by　the　rearrangement　of　molecules　in　binders,　and　it　can　make　the　inner　structure　of　binders　getting　stable　and　increase　the　fatigue　properties　of　asphalt　binders.　But　fatigue　damage　occurs　when　fatigue　tests　start,　no　matter　the　phenomenon　of　cyclic　hardening　happens　or　not.　If　the　controlled　load　is　low,　the　effect　of　rearrangement　of　molecules　on　material　is　beyond　the　effect　of　fatigue　damage　so　that　the　cyclic　hardening　can　be　observed.　When　the　load　conditions　get　worse,　the　effect　of　slight　fatigue　damages　produced　in　hardening　stage　will　show.