A regenerating method for activated alumina used in regenerating working fluid of hydrogen peroxide comprises the following steps: adding deactivated alumina discharged from a regenerating bed for working fluid of hydrogen peroxide with fire resistant alumina into a reactor through the top of the reactor and settling by gravity, oxidizing atmosphere entering into the reactor from the bottom of the reactor and running upwardly, discharging regenerated alumina and fire resistant alumina through the discharging device on the bottom of the reactor, discharging exit gas through the discharge port on the top of the reactor, the reaction temperature ranging from 360-800° C., the residence time of solid feed in the reactor ranging from 3-15 h. The method is economic, environment-protective, safe, and low-costly. The regenerated alumina will not poison palladium catalyst.