This project proposes a novel interleaved three phase PWM single stage resonant AC-DC converter with high frequency isolation. The proposed converter comes from an interleaved three phase PFC semi-stage and a three phase LLC resonant DC-DC semi stage. Soft switching commutation can be achieved on the power switches in this converter including zero voltage switching on the primary side power switches and zero current switching off on the secondary diodes. The LLC resonant tank in the DC-DC semi stage serves as a band-pass filter, which attenuates the line frequency ripple and keeps the switching frequency component passing through the transformer. The transformer is a high frequency transformer which keeps in a small size. Steady state analysis of the resonant DC-DC semi stage for PWM control is proposed to analyze the dc-link voltage stress. Moreover, the dc-link capacitor value can be greatly reduced without affecting the PFC operation. A prototype that converts a wide three phase input voltage to 300V dc output voltage was built and tested. The experimental results present an almost unity power factor with a conversion efficiency as high as 96.3% with total harmonic distortion (THD) as low as 3.86% at full load condition.