A direct current-direct current conversion circuit includes: an input inductor, a first capacitor, a second capacitor, a flying capacitor, a first switch, a second switch, a first inductor, a first diode, a first buffer circuit, a third switch, a fourth switch, a second inductor, a second diode, and a second buffer circuit. A power supply, the input inductor, the first diode, the second diode, the first capacitor, and the second capacitor are sequentially connected in series. A first terminal of the flying capacitor is connected between the first diode and the second diode. A second terminal of the flying capacitor is connected between the first switch and the third switch, and the second terminal of the flying capacitor is further connected between the second switch and the second inductor.