This study is an investigator-initiated, multicenter, prospective, open-label, endpoint-blinded, randomized controlled trial (PROBE design) that includes patients with moderate or severe symptomatic intracranial large vessel atherosclerotic stenosis (sICAS) who present with acute ischemic stroke within 48 hours of symptom onset. Patients will be centrally randomized in a 1:1 ratio into two groups: Experimental Group: A single subcutaneous injection of 420 mg evolocumab upon admission, combined with standard doses of atorvastatin 20 mg or rosuvastatin 10 mg, along with other standard guideline-based medical treatments. Control Group: Standard doses of atorvastatin 20 mg or rosuvastatin 10 mg, with the remainder of treatment based on current guidelines. The primary objective of the study is to evaluate whether early combination therapy with a PCSK9 inhibitor and statins within 48 hours of symptom onset can reduce the incidence of early neurological deterioration in patients with symptomatic intracranial atherosclerotic stenosis (sICAS). The secondary objectives include comparing the effects of early PCSK9 inhibitor and statin combination therapy versus statin monotherapy on the 90-day neurological outcomes of AIS patients, improving early neurological recovery, and reducing the recurrence rate of stroke at 30 and 90 days. The safety objective is to assess whether the combination of early PCSK9 inhibitors and statins, compared to statin monotherapy, increases the incidence of moderate-to-severe systemic bleeding within 3 days post-randomization (based on the GUSTO scale), any type of intracranial hemorrhage (according to the ECASS III criteria), and all-cause mortality within 90 days.