Left atrial appendage occlusion is a common procedure for patients with atrial fibrillation history when they underwent cardiac surgery. Before the LAAOS Ⅲ research results, this operation has been lacking strong evidence-based support. LAAOS Ⅲ is a prospective, double-blind, international multicenter, randomized blinded trial. According to the results of LAAOS Ⅲ, the left atrial appendage occlusion can reduce the risk of stroke and systemic embolism. This article will perform detailed interpretation of LAAOS Ⅲ research.