Abstract: A single-stage high frequency resonant AC/AC converter transfers AC-line input voltage into high frequency sinusoidal output voltage, which consists of two power conversion units, that is, power factor correction unit and high frequency resonant DC/AC unit, and it can be used to derive a modular multi-channel constant current LED driver. By adopting a full-bridge resonant converter to reduce the THD of the output voltage, a single-stage full-bridge high frequency resonant AC/AC converter was proposed in this paper. The operating principle was described and the performance analysis was presented in detail. Moreover, the quantitative parameter design method of the main circuit was presented, which was suitable for other single-stage AC input converters, such as single-stage PFC rectifier. Finally, a 200 W prototype has been built and tested to verify the correction of theory analysis and parameter design related. The experimental results show that the input power factor is around 0.93 and the maximum voltage of the DC bus capacitor is 440 V, moreover, the THD（total harmonics distortion,THD）of the output voltage is below 5%, which meet the practical application requirements.