Patients always have pain on the left side of the head, mainly consider the following aspects: First, the most common one is migraine, the headache is mostly on one side of the head with seizure-like, throbbing and throbbing pain, usually accompanied by nausea and vomiting, and the headache is aggravated by sound and light stimulation, easily triggered by inattention to diet, exertion and mental tension, and can be relieved after rest in a quiet environment. The headache can be relieved after resting in a quiet environment. About 2/3 of migraine patients have a positive family history of the disease. Secondly, if the patient always has pain on the left side of the head, it is also necessary to consider whether it is caused by cerebrovascular aneurysm, and it is recommended that the patient must improve this examination to clarify, because cerebral aneurysm has the risk of causing cerebral hemorrhage.