At　present,　the　most　of　LED　driver　on　the　market　is　designed　for　worldwide　line　(90Vac　similar　to　265Vac)　applications,　and　can　not　meet　the　higher　voltage　input　applications.　Therefore,　step-down　Cuk　PFC　is　proposed　to　be　used　in　higher　voltage　input　applications　(277-480Vrms)　in　the　paper.　A　half-bridge　LLC　was　used　as　a　DC-DC　isolation　unit　of　the　single-stage　converter　and　adopts　an　APWM-PFM　hybrid　control　strategy　to　solve　the　problem　that　the　conventional　pulse　frequency　modulation　(PFM)　control　strategy　leads　to　unsatisfactory　input　characteristics　of　the　single-stage　circuit　and　keep　the　LLC　circuit＇s　soft　switching　characteristics.　Therefore,　the　single-stage　resonant　converter　proposed　in　this　paper　possess　the　advantages　such　as　low　input　and　output　current　ripple,　low　stress　of　the　power　switch　and　high　system　efficiency　etc.　A　100W　experimental　prototype　was　built　in　the　laboratory,　which　verifies　the　feasibility　of　the　proposed　scheme.　Within　the　entire　input　voltage　range,　the　zero-voltage　switch-on　of　the　switch　and　the　zero-current　switch-off　of　the　secondary　diode　was　obtained　and　the　system　efficiency　achieves　up　to　91.65%　@　the　310Vrms　input　voltage　and　rated　load.