Objective To investigate cognitive dysfunction in patients with carotid artery stenosis (CAS) and potential risk factors related to cognitive-especially memory-dysfunction. Methods Forty-seven patients with carotid artery stenosis were recruited into our study cohort. The Mini-Mental State Examination (MMSE) and the Montreal Cognitive Assessment (MoCA) were adopted to assess cognitive function, the Wechsler Memory Scale (WMS) to assess memory function, high-resolution MRI and enhanced ultrasound to evaluate carotid plaques, and computed tomography perfusion (CTP) imaging to evaluate intracranial blood perfusion. Single-factor analysis and multiple-factor regression analysis were used to analyze potential risk factors of cognitive impairment. Results Mini-Mental State Examination test results showed that 22 patients had cognitive impairment, and MoCA test results showed that 10 patients had cognitive impairment. Analysis of various risk factors indicated that the average memory quotient of female patients was higher than that of males (P = 0.024). The cognitive and memory performance of those with an educational background above high school were significantly better than those of participants with high school or lower (P = 0.045). Patients with abnormal intracranial perfusion performed worse on the MMSE test (P = 0.024), and their WMS scores were significantly lower (P = 0.007). The MMSE scores and the memory quotients were significantly lower in patients with a history of cerebral infarction (MMSE, P = 0.047, memory quotient score, P = 0.018). Conclusion A history of cerebral infarction and abnormal cerebral perfusion are associated with decline in overall cognitive function and memory in patients with carotid stenosis. Being female and having an educational background above high school may be protective factors in the development of cognitive dysfunction.