Inclusion Criteria:
1. Age ≥18 years.
2. Having anterior circulation AIS within 24 hours of onset.
3. The NIHSS score at enrollment is 4 to 25.
4. Receiving intravenous recombinant tissue plasminogen activator (rt-PA) or TNK-tPA, or endovascular treatment including intra-arterial thrombolysis, mechanical thrombectomy, or intravenous rt-PA /TNK-tPA bridging endovascular treatment.
5. Being independent in daily activities (mRS ≤1) before onset.
6. Patients or their legal representatives are able and willing to sign informed consent forms.
Exclusion Criteria:
1. Having an Alberta Stroke Program Early Computed Tomography Score (ASPECT) score of 6 or less confirmed by preoperational computed tomography scan.
2. Being already treated with HUK or any drugs containing HUK after onset.
3. Having an allergy history of HUK or drugs containing HUK, or other drugs and food.
4. Having a history of coagulation dysfunction, systemic bleeding, or thrombocytopenia; having hemorrhagic diseases at the time of enrollment, including cerebral hemorrhage, subarachnoid hemorrhage, epidural or subdural hematoma, gingival bleeding, gastrointestinal bleeding, dermal ecchymosis, etc; taking anticoagulants including warfarin, rivaroxaban, etc.; or taking heparin within 48 hours after stroke onset.
5. Taking angiotensin-converting enzyme inhibitor (ACEI) antihypertensive drugs regularly within one week before enrollment, including captopril, enalapril, benazepril, etc.
6. Having chronic liver disease or liver dysfunction, with elevated ALT/AST (\>3.0×ULN ); or having kidney dysfunction or receiving dialysis, with elevated serum creatinine (\>2.0×ULN).
7. Having severe cardiopulmonary disease that are deemed unsuitable for the study by the investigators.
8. Having contraindications for intravenous thrombolysis or endovascular treatment, including intra-arterial thrombolysis, mechanical thrombectomy, or intravenous rt-PA /TNK-tPA bridging endovascular treatment.
9. Having lethal diseases with a life expectancy \< 3 months.
10. Being pregnant or lactating; or women of child-bearing age not taking effective contraception, or having no negative pregnancy test record.
11. Being unable to complete the study due to mental illness, cognitive or emotional disorder, physical condition, geographical factors, etc.
12. Participating in another clinical trial currently.
13. Other conditions that investigators consider he/she is not appropriate to participate in this study.
