The invention relates to a DC-DC converter and a control method thereof. The DC-DC converter includes: a clamp capacitor having one terminal connected to a ground terminal of a voltage source; a switching circuit including a first switch and a second switch connected in series to each other between a positive terminal of the voltage source and a ground terminal, and a third switch and a fourth switch connected in series to each other between both terminals of the clamping capacitor; and a forward-flyback transformer including a plurality of primary coils connected between a first connection node between the first switch and the second switch and a second connection node between the third switch and the fourth switch.