The study is a prospective, multi-center, stratified randomized, single-blind, parallel assignment, active control, non-inferiority trial. Patients are randomized 1 : 1 to either stent retriever(TonbridgeMT) or Solitaire™ for endovascular therapy for AIS. The study aims to evaluate the benefit and safety of stent retriever(TonbridgeMT) for AIS therapy, as compared to Solitaire™.

The main objective is to determine whether stent retriever(TonbridgeMT) will have non-inferior successful recanalization rate compared to Solitaire™ when applied to endovascular therapy for AIS.

The secondary objectives is to verify whether there isn't significant differences in time to achieve recanalization, NIHSS score, mRS score, and transportation performance between stent retriever(TonbridgeMT) and Solitaire™ when applied to endovascular therapy for AIS.

The third objectives is to verify whether there isn't significant differences in the rate of symptomatic intracranial hemorrhage, subarachnoid hemorrhage, adverse event(AE), serious adverse event(SAE), actual condition of AE and device deficiencies between stent retriever(TonbridgeMT) and Solitaire™ when applied to endovascular therapy for AIS.

Inclusion Criteria:

1. 18≤ages≤80;
2. Baseline NIHSS score obtained prior to randomization must be lower than 30 points;
3. Acute occlusion(TICI 0-1) of the intracranial segment of internal carotid artery(ICA), or M1/M2 middle cerebral artery(MCA), or A1/A2 anterior cerebral artery(ACA), as evidenced by digital subtraction angiography(DSA);
4. Patient treatable within 6 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;
5. Pre-AIS mRS score lower than 2.

Exclusion Criteria:

1. Computed tomography (CT) or magnetic resonance imaging (MRI) evidence of intracranial hemorrhage or massive cerebral infarction (ASPECTS score of<6 or infarct volume≥70ml or volume>1/3 blood supplying areas of MCA on CT/diffusion weighted imaging(DWI);
2. DSA evidence of simultaneous acute bilateral carotid occlusion;
3. DSA evidence of occlusions in the initial segment of carotid artery or carotid artery dissection or arteritis;
4. DSA evidence of tortuosity of cervical vessels precluding device delivery/deployment;
5. Hypertension (Systolic blood pressure(SBP)>185 mm Hg or diastolic blood pressure(DBP)>110 mm Hg) after using drug;
6. Platelet count<40,000/μL and use of Novel Anticoagulant with International Normalized Ratio(INR)>3.0;
7. Random blood glucose of<2.7mmol/L or>22.2mmol/L;
8. 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, myocardial infarction within the past 12 months before enrollment, history of sever psychosis);
9. Patients who will not cooperate or tolerate interventional operation;
10. Anticipated life expectancy of less than 90 days;
11. Allergy to contrast medium;
12. Females who are pregnant or breastfeeding;
13. Participation in any other clinical trial within the past 1 months before screening and follow-up;
14. The patient or the patient's legally authorized representative hasn't signed and dated an informed consent form;
15. Other factors that would cause harm or increased risk to the participant or close contacts, or preclude the participant's full adherence as per investigator's judgement.