A left atrial appendage occluder (200) comprises a sealing part (220), a fixing part (210) disposed at one side of the sealing part (220), and a connection part (230) for connecting the sealing part (220) and the fixing part (210). The radial deformation capacity of the sealing part (220) is greater than the radial deformation capacity of the fixing part (210), and/or, the axial deformation capacity of the sealing part (220) is greater than the axial deformation capacity of the fixing part (210). In the left atrial appendage occluder (200), the radial or axial deformation capacity of the sealing part (220) is configured to be greater than the radial or axial deformation capacity of the fixing part (210), thereby avoiding the situation in which the sealing part (220) is not optimally fitted with the opening of the left atrial appendage (10) when the fixing part (210) is placed inside of the left atrial appendage (10), which in turn enhances the occlusion effect. Additionally, the sealing part (220) has great deformation capacity which reduces the risks of the sealing part (220) causing abrasion to the opening of the left atrial appendage, or even damaging the opening of the left atrial appendage. The fixing part (210) not only avoids the risks, but also fixes the occluder in the left atrial appendage (10) more effectively, and prevents the occluder (200) from being disengaged from the left atrial appendage.
