A new isolated bridgeless PFC converter based on active-clamped SEPIC is proposed. Compared to conventional active-clamped SEPIC PFC converter， the proposed converter reduces conduction loss by removing two diodes in the line cur-rent path， while preserving the advantages of the active-clamped SEPIC such as zero-voltage switching (ZVS) and active voltage clamp for all the high frequency switches， soft turn-off of the out-put diodes and well damped control-to-input-current response. In addition， the peak voltage stress on the output diode is inherently clamped by the center-tapped transformer configuration. Exper-imental results from a 3.3 kW prototype verified the operation of the converter and demonstrated peak efficiency of 97.26%with 140 kHz switching frequency. The power density of the sin-gle-phase PFC module is 101 W/in'。