This multicenter, prospective, double-blind, placebo-controlled, randomized trial (ANGEL-DRUG2) aims to evaluate the efficacy and safety of intravenous tirofiban following intravenous thrombolysis in patients with acute ischemic stroke who show insufficient neurological improvement after initial treatment. Eligible patients (≥18 years, baseline NIHSS ≥4, within 4.5 hours from last known well) will be randomized 1:1 to receive either tirofiban or placebo infusion for 24 hours, followed by standard oral antiplatelet therapy. The primary endpoint is the proportion of patients achieving functional independence (mRS 0-2) at 90 days. Secondary outcomes include changes in NIHSS score, vessel recanalization, infarct volume, distribution of mRS scores, recurrent stroke, and health-related quality of life. Safety outcomes focus on symptomatic intracranial hemorrhage and all-cause mortality. Approximately 976 patients will be enrolled across 30 sites in China.