A multi-phase boost converting apparatus includes a multi-phase boost converter and a passive lossless snubber, wherein the passive lossless snubber includes a first resonant capacitor, a second resonant capacitor, an output-end first unidirectional conduction component, an output-end second unidirectional conduction component, an input-end first unidirectional conduction component, an input-end second unidirectional conduction component and a resonant inductor.