Investigated and analyzed the activity of ethyl acetate extract of chestnut shell and the components by UPLC—MS/MS. Antioxidant activities were carried out by DPPH radical scavenging assays and ABTS radical scavenging assays. The inhibitory activity of alpha glycosidase enzymes was measured by PNPG method. Qualitative analysis was performed by UPLC—MS/MS for analysis of major active components in ethyl acetate extracts. It determined that ethyl acetate extracts of Chestnut shell possessed remarkable DPPH radical scavenging activity, ABTS radical scavenging activity and high inhibitory activity of alpha glycosidase enzymes owing to the fat-soluble flavonoids are the main active components.