A　new　cascade　buck-boost　topology　with　passive　lossless　snubber　is　proposed　in　this　paper,;　it　has　been　successfully　used　in　PFC　circuit　of　high　voltage　system.　Switching　losses　and　EMI　noises　are　reduced　by　restricting　di/dt　of　the　diode　reverse　recovery　current　and　dv/dt　of　IGBT　collector-emitter　voltage.　The　IGBT　in　the　buck　circuit　operates　at　ZVS　turn-off　and　ZCS　turn-on.　The　freewheeling　diode　is　also　commutated　with　ZVS.　An　APFC　prototype　has　been　built　in　the　laboratory　to　demonstrate　the　effects　of　the　circuit.　Power　factor　of　this　380VAC/600W　proof-of-prototype　is　0.98　and　less　than　11%　THD　can　be　achieved.