The present invention relates to a method for preparing hexafluoropropylene oxide with high yield, and particularly to a method for preparing hexafluoropropylene oxide comprising the step of performing a two-phase interfacial reaction between an organic phase containing hexafluoropropylene and an aqueous phase containing a hypochlorite oxidant in the presence of a phase-transfer catalyst and a non-ionic surfactant to improve the degree of emulsification and dispersion of the organic phase and to increase the contact interfacial area, thereby increasing the efficiency and the yield of the reaction.