A DC conversion circuit in the disclosure includes a buck-boost converter and a resonant stage circuit. The buck-boost converter has two input ends, a negative output end and a positive output end. The buck-boost converter receives a first DC signal via its two input ends, and outputs a second DC signal via its two output ends. The resonant stage circuit has two input ends and two output ends. The resonant stage circuit receives the second DC signal via its two input ends, converts the second DC signal into energy for power charging, and outputs the energy to a load via its two output ends. Then, the resonant stage circuit converts the energy, which is used for power charging, to form a negative voltage by a resonance effect, and outputs the energy to the load via its two output ends.