Stroke is one of the high-risk diseases leading to global mortality and disability. Beyond conventional pharmacological therapy and endovascular treatment, hyperbaric oxygen therapy (HBOT), as one of the recent hot research directions, has been widely applied in multiple clinical fields, including carbon monoxide poisoning, arterial gas embolism, hearing loss, gas gangrene, skin grafting, radiation injury, and traumatic brain injury. However, the evidence supporting HBOT as a treatment modality for ischemic stroke still needs to be further strengthened. Through a literature review, this article explores the beneficial mechanisms of HBOT for ischemic stroke from the perspective of basic research, including anti-neuroinflammation, elevation of oxygen partial pressure and oxygen saturation, anti-oxidative stress, modulation of red blood cells, reduction of apoptosis and necrosis, promotion of angiogenesis, improvement of cerebral tissue energy metabolism, neuronal repair, promotion of neurogenesis, and protection of the blood-brain barrier.