CLLC resonant converter normally faces light-load problems on voltage regulation and efficiency. This paper presents a novel asymmetric pulse width modulation (APWM) control scheme to improve the voltage regulation ability and efficiency of full-bridge CLLC resonant converter under light-load conditions. In this control scheme, the proposed APWM method can reach the desired voltage gain lower than unity at resonant frequency with soft switching of all switches achieved in light-load conditions, and the pulse frequency modulation (PFM) is combined to realize the voltage gain higher than unity. Therefore, the proposed control scheme can well regulate the output voltage and achieve satisfying efficiency over entire load conditions. This control scheme is verified by experiments on a 21.5V/380V and 200W GaN based full bridge CLLC converter prototype, proving desirable voltage gain and favorable efficiency from light-load to full-load conditions.