Smog is an uncommon cerebrovascular disease, mainly due to chronic progressive stenosis or occlusion of major bilateral branch vessels of the cerebral arterial ring, which then triggers compensatory proliferation of the vascular network at the base of the skull, forming a fragile network of tiny vessels that resembles a cloud of smoke when imaged on cerebral angiography, hence the name smog. It can be seen that smog is a progressive disease, and if left untreated it will get worse and may even be life-threatening. Some patients are lucky enough to ask if they have survived more than 20 years with smog, but the chances are slim. Smog can cause cerebral infarction or hemorrhage at any time, and sometimes the onset of the disease can be sudden and without any warning, ranging from dizziness and weakness to disability and death. Therefore, once a diagnosis of smog is made, it should be treated with surgery as soon as possible. For the treatment of smog, it is recognized that conservative medical treatment is not very useful and can only relieve the symptoms at the beginning of the disease process, but the long-term effect is not good. Therefore, surgery is the only way to treat smog. The traditional surgical treatment for smog is direct bypass surgery and patching, but direct bypass surgery or patching alone has its limitations in terms of blood supply improvement and time to effect, and cannot achieve very satisfactory results. Combined vascular bypass surgery is a more advanced and effective surgical procedure, which is a combination of both direct bypass and patching in the same surgery. It can rapidly reconstruct the main vascular channel and improve blood supply immediately, and at the same time, it can also induce the formation of new blood vessels by multifactorial patching on the brain surface, which can further expand the scope of blood supply improvement and achieve better surgical results.