Inclusion Criteria:  Patients who voluntarily participate and sign the informed consent and are able to comply with the entire trial process; Age ≥ 70 years; Patients with severe calcific aortic stenosis confirmed by echocardiography (Transaortic flow velocity ≥ 4.0 m/s, or aortic-valve gradient ≥ 40 mmHg (1 mmHg = 0.133 kPa), or aortic valve area < 0.8 cm2, or effective orifice area < 0.5 cm2/m2); Patients who have symptoms obviously caused by aortic stenosis, NYHA Class II or worse; Patients who are unsuitable for conventional surgery evaluated by the cardiac team (including at least two cardiovascular surgeons) [13] *; Life expectancy after implantation of prosthetic valve is more than one year evaluated by the cardiac team (including at least two cardiac surgeons); Aortic annulus diameter ≥ 18 mm and ≤ 29 mm (measured by cardiac CT);  Ascending aorta diameter < 50 mm  *: If the patient meets any of the following criteria judged by a multidisciplinary cardiac team composed of cardiologists and cardiovascular surgeons, radiologists, anesthesiologists, etc. (at least two cardiovascular surgeons), the patient will be identified as unsuitable for conventional surgery (at least STS ≥ 8 points):  Estimated risk of surgery-related death or disability > 50% within 1 year; ≥3 major organ damage that could not be improved by surgery; Obstacles related to surgical procedures judged as serious  Exclusion Criteria:  Patients with bacteremia or toxemia; Previous endocarditis or active endocarditis; Acute myocardial infarction (Q-wave MI, or non-Q-wave MI with elevated creatine kinase isoenzyme and troponin T) within 30 days; Any intracardiac mass, left ventricular or atrial thrombus, vegetation on echocardiography; Symptomatic atrial fibrillation that cannot be improved by drug therapy; Familial hypertrophic cardiomyopathy; Mitral or tricuspid valve insufficiency (grade II regurgitation or higher); Previous aortic valve graft (mechanical or bioprosthetic valve); Known allergies to contrast agents, aspirin, heparin, ticlopidine drugs, nitinol shape memory alloy, or bovine products; Known contraindications or allergies to anticoagulant regimens, or inability to use anticoagulants throughout the trial; Other serious diseases that may reduce life expectancy to less than 12 months (such as clinically recurrent or metastatic cancer, congestive heart failure, etc.); Current substance abuse problems (e.g., alcohol, cocaine, heroin, etc.); Scheduled to undergo surgery that may result in protocol noncompliance or confounding in data interpretation. Cerebrovascular accident (CVA) in the past 6 months; Patients with common carotid artery or internal carotid artery or vertebral artery stenosis (>70%); White blood cell count <3×109/L, platelet count <50×109/L; Hemoglobin < 90 g/L; Patients with severe coagulopathy; Severe left ventricular dysfunction, left ventricular ejection fraction < 20%; Abdominal or thoracic aortic aneurysm; Hepatic encephalopathy or acute active hepatitis; On dialysis or baseline creatinine level > 2.5 mg/dL (221 μ mol/L); Bleeding tendency or history of coagulation disease or refusal of blood transfusion; Patients with active peptic ulcer or active gastrointestinal (GI) bleeding; Patients with neurological diseases that seriously affect mobility and activities of daily living; Patients with mental illness or psychological disorders who are unable to communicate effectively; Patients who need emergency surgery for any reason; Patients who have participated in other drug or medical device clinical trials within 3 months prior to screening; Other conditions that make the patient ineligible to participate in this clinical trial in judgement of investigators