Disclosed are a DC-DC converter and a power supply device. The converter includes: a power input end; a power output end; M bridge arm circuits; a transformer component; a rectification and filtering circuit, wherein input ends of the rectification and filtering circuit are connected to secondary winding connection ends of the transformer component, and an output end of the rectification and filtering circuit is connected to the power output end. The M bridge arm circuits and the transformer component are configured to convert the input DC power supply into the required voltage on the secondary windings of the transformer component, and the required voltages are rectified and filtered by the rectification and filtering circuit, and the filtered voltage is output to the power output end, where M is greater than or equal to 3.