Stroke is the leading cause of death and disability in China. Among the stroke patients, cryptogenic stroke without definite causes accounted for about one third. The incidence of patent foramen ovale (PFO) in patients with cryptogenic stroke is higher than that in patients with clear cause of stroke, which is an important risk factor in cryptogenic stroke. The main pathogenesis of stroke in patients with PFO is paradoxical embolism. In clinical practice, contrast-enhanced transcranial Doppler, contrast-enhanced transthoracic echocardiography, and contrast transesophageal echocardiography are frequently used to detect PFO. In recent years, a number of large-scale randomized controlled trials have shown that percutaneous foramen ovale occlusion combined with drug therapy significantly reduced the incidence of recurrent strokes in patients with cryptogenic stroke compared with drug therapy alone.