Stent Retriever for Thrombectomy Revascularisation of Large Vessel Occlusions in Acute Ischemic Stroke(Catfish)

Inclusion Criteria: 1. 18≤ages≤80; 2. mRS score must lower than 2 Pre-AIS(acute ischemic stroke). 3. Baseline NIHSS score obtained prior to randomization must be between 8 and 25; 4. Symptoms and signs in accordance with Large vessel occlusion, confirmed by CTA(CT angiogram)/MRA(magnetic resonance angiography )/DSA; 5. Patient treatable within 8 hours of symptom onset (symptoms onset is defined as point in time the patient was last seen well (at baseline)) can accept the complete femoral artery puncture; 6. Baseline Alberta stroke program early CT score (ASPECTS) or posterior circulation Alberta stroke program early CT score (pc-ASPECTS)≥ 6 on Computed tomography (CT) or magnetic resonance imaging(MRI). 7. The patient or relative give written informed consent. Exclusion Criteria: 1. History of stroke in past 3 months. 2. Presumed septic embolus, or suspicion of bacterial endocarditis. 3. Evidence of tortuosity of cervical vessels precluding device delivery/deployment; 4. Hypertension (Systolic blood pressure(SBP)\>185 mmHg or diastolic blood pressure(DBP)\>110 mm Hg) after using drug; 5. Platelet count\<30,000/μL and use of Novel Anticoagulant with International Normalized Ratio(INR)\>3.0; 6. Random blood glucose of\<2.7mmol/L or\>22.2mmol/L; 7. Patients with heart or lung or liver or renal failure or other sever disease (intracranial tumors, cerebral arteriovenous malformation (AVM), systemic infection, active disseminated intravascular coagulation, history of sever psychosis); 8. Patients with Dementia or psychiatric disease that would confound the neurological or functional evaluations. 9. Anticipated life expectancy of less than 6 months; 10. Known serious sensitivity to contrast medium and nitinol metal; 11. Females who are pregnant or breastfeeding; 12. Current participation in any other clinical trial; 13. The patient or the patient's legally authorized representative hasn't signed and dated an informed consent form; 14. Rapidly improving neurologic examination. 15. Excessive vascular access tortuosity that will likely result in unstable access platform. 16. Seizures at stroke onset which would preclude obtaining a baseline NIHSS. 17. Suspected intracranial dissection or cerebral vasculitis. 18. Evidence of tandem cervical occlusion, or stenosis requiring treatment. 19. Major surgery or significant trauma in the past 30 days or plan to have surgery in next 3 months after enrolled. 20. CT or MRI evidence of mass effect or intra-cranial tumour (except small meningioma) 21. Any type of cerebral hemorrhage (only microbleeds are allowed) on neuroimaging 22. The subject is not appropriate for mechanical thrombectomy intervention in the opinion of the investigator.