The intravenous administration of abundant normal saline is an easy-to-use strategy commonly employed to expand the blood volume. This study aimed to evaluate the efficacy and safety of the early administration of an abundant normal saline infusion after intravenous thrombolysis for promoting functional independence in patients with acute ischemic stroke. This multicenter, randomized, phase III clinical trial intends to enroll stroke participants who have undergone intravenous thrombolysis. Eligible patients are randomized to receive either abundant intravenous normal saline infusion (2,000-2,500 mL; normal saline group) or a small volume of intravenous normal saline infusion (≤600 mL; control group) immediately after thrombolysis. The primary outcome is the comparison of the ordinal modified Rankin Scale score at 90 days (±3) after randomization between the treatment groups.

Inclusion Criteria:

1. Age 18 to 80 years.
2. Acute ischemic stroke treated with intravenous thrombolysis.
3. Prestroke mordified Rankin Scale score ≤1;
4. Admission NIHSS score 4-25, with NIHSS 4-5 requiring the presence of a disabling deficit as defined in the 2026 AHA/ASA Guideline for the Early Management of Patients With Acute Ischemic Stroke.
5. Onset-to-needle time≤4.5 hours or DWI-FLAIR mismatch (guided by MRI evaluation) for patients with uncertain stroke onset time according to the inclusion criteria of the WAKE-UP study.
6. Signed informed consent.

Exclusion Criteria:

1. Contraindications to intravenous thrombolysis.
2. Planned endovascular treatment prior to enrollment.
3. History of heart failure, or pre-enrollment brain natriuretic peptide (BNP) ≥100 pg/mL, or clinical presentations or signs suggestive of heart failure.
4. History of atrial fibrillation, or pre-enrollment electrocardiogram indicating atrial fibrillation.
5. History of valvular heart disease or valve replacement surgery, suggesting cardioembolic stroke.
6. History of renal dysfunction, or pre-enrollment serum creatinine >133 μmol/L, or estimated glomerular filtration rate (eGFR) <60 mL/min/1.73 m².
7. Severe hemorrhage prior to enrollment, including symptomatic intracranial hemorrhage, gastrointestinal bleeding, respiratory tract bleeding, or massive skin and mucous membrane bleeding.
8. Premature termination of intravenous thrombolysis due to any reason, such as hemorrhage, allergic reaction, or seizure.
9. Participation in another clinical trial within the previous 3 months.
10. Poor compliance, or inability to adhere to the trial protocol or complete follow-up.