Background: The proportion of dementia patients in Asian countries is rapidly increasing, and because vascular dementia is more common than in the West, it is recognized as important as Alzheimer’s disease. Purpose: The aim of this study was to verify the benefits of Pinellia ternata Breitenbach tuber aqueous extract (PTex) in improving cognitive function and reducing inflammation in brain damage resulting from bilateral common carotid artery stenosis (BCAS). Materials and methods: Four groups of five C57BL/6 male mice each were randomly assigned (a sham group, a BCAS surgery group, and two experimental groups that received PTex concentrations of 25 and 50 mL/kg, respectively). Measuring behavioral learning and memory, the two concentrations of the extract were given orally three times a week for six weeks following BCAS surgery. Furthermore, the inflammatory response in the cerebral cortex was observed, and RNA sequencing analysis was carried out. Results: The novel object recognition test revealed that the PTex-50-treated group had improved cognitive function, and the anti-inflammatory effect was confirmed by immunofluorescence staining of brain tissue. Proteins such as Apob, Shh, Dscc1, Cdc45, and Cdc6 were identified through protein-protein interaction network analysis as having a beneficial effect on BCAS-induced cognitive deficit. Conclusion: Results show that PTex-50 was found to have a beneficial effect on BCAS-induced cognitive deficit.