Inclusion Criteria:  Clinical diagnosis of ischemic stroke with National Institutes of Health Stroke Scale (NIHSS) score of 1-15 Ischemic lesions on diffuse-weighted imaging located in the territory of symptomatic intracranial atherosclerosis (ICAS). Symptomatic ICAS (above 30%) at the M1 or M2 of the middle cerebral artery, basilar artery or at the intracranial portion of the internal carotid artery. Serum LDL-C ≥70 mg/dL for subjects on lipid-lowering therapies (such as a statin and/or ezetimibe) or LDL-C ≥100 mg/dL for subjects without lipid-lowering therapies. Ability to randomize within 7 days of time last known free of new ischemic symptoms. Ability to receive alirocumab or statin treatment within 7 days of stroke onset. Head CT or MRI ruling out hemorrhage or other pathology, such as vascular malformation, tumor, or abscess, that could explain symptoms or contraindicate therapy. Pre-stroke modified Rankin Scale (mRS)≦2  Exclusion Criteria:  Age <20 years. Judged by clinical physician. After endovascular intervention or endarterectomy for the symptomatic ICAS. Patients with more than 50% stenosis of extra-cranial arteries the relevant arteries on magnetic resonance angiography (MRA), including extra-cranial carotid artery or vertebral arteries. Patients with high risk of cardioembolic source, such as atrial fibrillation, acute myocardial infarction, severe heart failure or valvular heart disease. Other determined stroke etiology, such as vasculitis, shock, antiphospholipid antibody syndrome, arterial dissection, CADASIL and etc. Qualifying ischemic event induced by angiography or surgery. Severe non-cardiovascular comorbidity with life expectancy <6 months. Contraindication or allergy to alirocumab or Gadolinium Severe renal (serum creatinine >2 mg/dL) or calculated glomerular filtration rate <30 mL/min/ 1.73 m2 by estimated glomerular filtration rate (eGFR) using Cockcroft Gault methodology. Hepatic insufficiency (INR>1.2; ALT>40 U/L or any resultant complication, such as variceal bleeding, encephalopathy, or jaundice) Hemostatic disorder or systemic bleeding in the past 3 months Current thrombocytopenia (platelet count <100 x109/L) or leukopenia (<2 x109/L) Anemia（<10 mg/dL） History of drug-induced hematologic or hepatic abnormalities History of malignancy that required surgery, radiation therapy or systemic therapy. Females who are pregnant or nursing, or who are of childbearing potential and unwilling to use effective contraception. Other neurological conditions that would complicate assessment of outcomes during follow-up.