Novel　circuit　structure　and　topologies　family　of　uninterruptible　AC　switching　power　supplies　with　high　power　factor　are　proposed.　The　circuit　structure　of　AC　switching　power　supplies　is　constituted　of　single　stage　uninterruptible　AC-DC　converter　with　high　power　factor　and　DC-AC　inverting　bridge.　The　voltage　mode　PWM　control　is　introduced　in　the　former　stage,　and　the　three-state　DPM　hysteresis　current　control　is　introduced　in　the　later　stage.　The　three　operational　modes　and　steady　principle　are　investigated.　Test　results　demonstrate　that　the　AC　switch　power　supply　has　some　advantages,　such　as　simple　topology,　high　power　density,　uninterruptible　power　supply,　high　power　factor,　fast　dynamical　response,　strong　sustaining　ability　under　over-load　and　short-circuit,　and　small　THD　of　output　voltage.