Alzheimer's disease (AD) is a complex neurodegenerative condition. 5α-epoxyalantolactone (5α-EAL), a eudesmane-type sesquiterpene isolated from the herb of Inula macrophylla, has various pharmacological effects. This work supposed to investigate the improved impact of 5α-EAL on cognitive impairment. 5α-EAL inhibited the generation of nitric oxide (NO) in BV-2 cells stimulated with lipopolysaccharide (LPS) with an EC50 of 6.2 μM. 5α-EAL significantly reduced the production of prostaglandin E2 (PGE2) and tumor necrosis factor-α (TNF-α), while also inhibiting the production of cyclooxygenase-2 (COX-2) and inducible nitric oxide synthase (iNOS) proteins. The ability of 5α-EAL to penetrate the blood-brain barrier (BBB) was confirmed via a parallel artificial membrane permeation assay. Scopolamine (SCOP)-induced AD mice model was employed to assess the improved impacts of 5α-EAL on cognitive impairment in vivo. After the mice were pretreated with 5α-EAL (10 and 30 mg/kg per day, i.p.) for 21 days, the behavioral experiments indicated that the administration of the 5α-EAL could alleviate the cognitive and memory impairments. 5α-EAL significantly reduced the AChE activity in the brain of SCOP-induced AD mice. In summary, these findings highlight the beneficial effects of the natural product 5α-EAL as a potential bioactive compound for attenuating cognitive deficits in AD due to its pharmacological profile.