Designing highly sensitive and selective assay for analyzing α-glucosidase activity is of critical value for diagnosis of related diseases. Herein, we proposed a biomineralization synthetic route to construct bovine serum albumin templated hybrid nanomaterials of Au nanoclusters (Au NCs) and oxygen deficient manganese dioxide (indicated as BAM). BAM exhibits ultra-fast oxidase (OXD)-like activity that directly oxidized TMB to generate product. Unexpected, the OXD-like activity of BAM is not relied on the reactive oxygen species or dissolved molecular oxygen, which has rarely been reported. The superior OXD-like activity of BAM is derived from the strong interactions between Au NCs and MnO2-x nanosheets that contributes to the partial reduction of MnO2-x and increase of Au(Ⅰ) species. And the catalytic mechanism is related to electron transfer from TMB to MnO2-x with Au NCs as intermediates. The analysis of α-glucosidase activity has been realized by BAM and 2-O-a-D-glucopyranosyl-L-ascorbic acid (AA2G) as the catalytic substrate with dual mode. The AA2G can be hydrolyzed by α-glucosidase into AA, which can obviously inhibit the oxidation of TMB and recover the fluorescence of Au NCs. And the inhibition ratio and recovery efficacy are related the activity of α-glucosidase. Hence, the activity of α-glucosidase can be analyzed by the changes of the signal of absorbance or fluorescence. The dual-mode detection can prevent false negative/ positive results, satisfying different demands in various analytical situation.