Objective To explore the characteristics of cognitive impairment and sleep disordersin patients with severe stenosis or occlusion of internal carotid artery. Methods Forty patients （case group） with severe internal carotid artery stenosis or occlusion were selected from January 2015 to June 2016 in Jiang-men City Central Hospital. Eighty patients with no stenosis of internal carotid artery were enrolled as controlgroup. The Montreal Cognitive Assessment scale （MoCA），Mini Mental State Examination （MMSE）and Pittsburgh Sleep Quality Index scale （PSQI）were assessed to measure the cognitive function and sleep quality in two groups. Results Scores of visual space structure and execution，attention，memory，language，abstract thinking， name，time and place of directional function and MoCA score were lower in case group than that in control group （P＜ 0.05）. Scores of orientation ability，language，memory，memory，calculation ability and MMSE scores were lower in case group than that in control group （P＜ 0.05）. Scores of sleep time，sleep efficiency，sleep time， sleep quality，daytime dysfunction and hypnotic drugs，PSQI scores were higher in case group than that in con-trol group （P＜ 0.05）. Conclusions Patients with severe stenosis or occlusion of internal carotid artery havecognitive impairment and decreased sleep quality.