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 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, then discharging exit gas and regenerated alumina through the discharge port on the top and discharging device on the bottom of the reactor respectively. The method is economic, environment-protective, safe, low-costly. The regenerated alumina will not poison palladium catalyst.