Obstructive sleep apnea (OSA) affects quality of life and health in nearly 1 billion patients all over the world. With aging society, OSA increases the risk of Alzheimer's disease and leads to severe cognitive impairment. Chronic intermittent hypoxia (CIH), the core pathological mechanism of OSA, may induce synaptic plasticity damage and cognitive impairment, and decrease learning and memory and attention ability. However, the molecular mechanism underlying OSA is still not fully understood. And, there is no targeted treatment strategy for cognitive impairment in patients with OSA. Firstly, the correlation between OSA and cognitive dysfunction was summarized in this review. Secondly, the molecular mechanism of CIH-induced cognitive impairment was elucidated from the perspectives of synaptic plasticity damage, oxidative stress, inflammation, endoplasmic reticulum stress, apoptosis, mitochondrial dysfunction and autophagy. Finally, the current treatment strategy for cognitive impairment in patients with OSA was summarized.