The left half of the headache, accompanied by nausea and vomiting, requires consideration of the following possible causes: 1. Cerebral hemorrhage: This is one of the most frequent causes of headache accompanied by nausea and vomiting. Improve the head CT examination, it can be found that the high-density shadow in the left side of the patient’s brain is a dominant manifestation of hemorrhage. Patients often have hypertension and other underlying diseases, after the onset of sudden onset of severe headache, can be accompanied by jet vomiting, and sometimes there is also impaired consciousness. 2, brain tumor: this patient is chronic progressive aggravation of the onset of the disease, to late symptoms will be accompanied by high cranial pressure performance, nausea, vomiting, and limb hemiparesis. Head MRI or CT can detect brain tumor, and enhancement examination can help to clarify whether it is malignant or benign. 3. Vascular headache: The patient has no positive neurological signs, and the headache has a history of recurrent attacks, and before the attack, there can be dizziness or blurred vision, flashing light, dark spots, visual distortion and other aura. The attack is accompanied by nausea and vomiting, but lasts from several minutes to tens of minutes can be relieved by itself, and there are no abnormalities in CT and MRI.