The purpose of this thesis is to improve the efficiency of the converter to improve the low-voltage, it will be divided the voltage of PFC into two sections with two stage input voltage. Using asymmetrical half bridge converter, which adopt one pair of transformer structure. When the input voltage is between ( and ), we boost it to , and when the input the voltage is between ( and ) we boost it to . The experimental results of the real implemented hardware obvious by demonstrate that the method can not only raise the efficiency but also reduce the losses of the converter.