In this paper, a high efficiency LLC resonant converter is presented. The burst mode control method is applied to reduce the losses and thus the efficiency of light load condition is improved. Especially, the effectiveness of burst mode frequency and switching frequency at light load condition are discussed and verified via experimental results. The experimental results show that the efficiency can be improved with appropriate burst mode frequency and switching frequency at light load condition. Finally, a laboratory prototype with 400V input and 24 V/10 A output is implemented that the efficiency is 94.52% at full load and 83.3% at 0.25 A load condition.