This is a prospective, multicenter, randomized, active controlled, clinical trial to evaluate the safety and effectiveness of the LAMax Left Atrial Appendage (LAA) Closure System.

This is a prospective, multicenter, randomized, active controlled, clinical trial to evaluate the safety and effectiveness of the LAMax Left Atrial Appendage Closure (LAAC) System. Subjects with non-valvular Atrial Fibrillation will be randomized in a 1:1 ratio to the Experimental Treatment Arm (LAMax LAAC system) or the Control Arm (Watchman LAAC system, Boston Scientific Inc., USA). The trial is designed to demonstrate that safety and effectiveness of the LAMax device are non-inferior to the Watchman device.

Inclusion Criteria:

• Patients ≥ 18 years old with non-valvular atrial fibrillation (AF) and CHA2DS2-VASc ≥2
• There is one of the following: (1) Not suitable for long-term standard anticoagulation treatment; (2) On the basis of long-term standardized anticoagulant therapy with warfarin, stroke or embolism still occurred; (3) HAS-BLED ≥ 3.
• Provide written informed consent and agree to comply with required follow-ups.

Exclusion Criteria:

1. . Patients with other diseases other than AF who need long-term warfarin anticoagulation therapy;
2. . Those who need selective cardiac surgery;
3. . Heart failure NYHA grade IV;
4. . AF caused by rheumatic valvular disease, degenerative valvular disease, congenital valvular disease, severe mitral stenosis, aortic stenosis, or other valvular diseases;
5. . The early onset of AF and paroxysmal AF with definite causes, such as secondary to coronary artery bypass grafting (CABG), hyperthyroidism;
6. . Patients with symptomatic carotid artery disease (such as carotid stenosis > 50%);
7. . Patients with acute myocardial infarction, unstable angina, or recent myocardial infarction < 3 months;
8. . Stroke or TIA within 30 days;
9. . Bleeding disease, coagulation-related diseases, and active peptic ulcer;
10. . Active endocarditis, vegetations, or other infections causing bacteremia or sepsis;
11. . Conditions may lead to difficulty in testing or significantly shorten the life expectancy of patients (< 1 year);
12. . Pregnant, lactating or planned pregnancy during the trial;
13. . Patients who have not reached the end of other clinical trials of drug or device;
14. . Hematological abnormality (WBC < 3 × 109 / L, HB < 90g / L, or platelet count < 50 × 109 / L or > 700 × 109 / L));
15. . Renal insufficiency (creatinine > 3.0mg/dl or 265.2umoi / L), and / or advanced renal diseases requiring dialysis;
16. . Severe liver dysfunction (AST / ALT is 5 times higher than the upper limit of normal value, or total bilirubin is 2 times higher than the upper limit of normal value);
17. . The investigator believes that the patient is not suitable to participate in the clinical trial.
18. . Left atrial appendage has been removed, post heart transplantation, post atrial septal repair, or post occluder implantation;
19. . Radiofrequency ablation in 30 days before and after the implantation of LAA occluder;
20. . Cardioversion within 30 days after the implantation of LAA occluder;
21. . Post prosthetic heart valve replacement;
22. . Allergic to or contraindication to metal nickel alloy, aspirin, clopidogrel, contrast agent, heparin and other anticoagulants, etc;
23. . Patients who have placed other instruments in the cardiovascular cavity and are unable to place the LAA occluder;
24. . LVEF（left ventricular ejection fraction ）<35%；
25. . Clear thrombus is found in the heart before device implantation;
26. . TEE examination: refer to Watchman LAAC requirement to measure the orifice diameter of LAA, the maximum diameter is less than 17 mm, or more than 31 mm;
27. . Patent foramen ovale with high risk;
28. . mitral stenosis with a valve area ≤ 2 cm2;
29. . left atrial diameter > 65mm, or pericardial effusion more than a small amount, the depth of local effusion > 10 mm;
30. . Contraindications to X-ray, or not suitable for TEE examination.