A replaceable left atrial appendage occluder, comprising: a stepped balloon, and an occlusion disc; wherein the stepped balloon and the occlusion disc are configured to be connected and fixed to each other, and disposed on a left side and a right side of a left atrial appendage, respectively, such that the left atrial appendage is pressed and occluded between the stepped balloon and the occlusion disc; the occlusion disc is an elastic umbrella-shaped mesh structure, and a barrier patch is disposed inside the occlusion disc; wherein the stepped balloon comprises a hollow structure, and the stepped balloon after being filled forms a left atrial appendage orifice occlusion portion and a left atrial anchor portion; a diameter of the left atrial appendage orifice occlusion portion is larger than a left atrial appendage orifice; the left atrial appendage orifice occlusion portion is configured to completely fill and occlude the left atrial appendage orifice; a diameter of the left atrial anchor portion is larger than the diameter of the left atrial appendage orifice occlusion portion; the left atrial anchor portion is configured to be clamped on a left atrial wall of the left atrial appendage orifice to prevent the stepped balloon from sliding into the left atrial appendage; and a balloon filling inlet is disposed on a surface of the left atrial anchor portion, and the balloon filling inlet is configured to inject a liquid into the stepped balloon; a movable cover membrane is disposed on the surface of the left atrial anchor portion; and the movable cover membrane is configured to seal a surface of the stepped balloon when in closed position; a penetrating passage is disposed in the stepped balloon; a side of the occlusion disc is provided with a connecting column, wherein the side of the occlusion disc is configured to contact the left atrial appendage; the stepped balloon and the occlusion disc are configured to be fixed to each other by an extension connection of the penetrating passage and the connecting column. a stepped balloon, and an occlusion disc; wherein the stepped balloon and the occlusion disc are configured to be connected and fixed to each other, and disposed on a left side and a right side of a left atrial appendage, respectively, such that the left atrial appendage is pressed and occluded between the stepped balloon and the occlusion disc; the occlusion disc is an elastic umbrella-shaped mesh structure, and a barrier patch is disposed inside the occlusion disc; wherein the stepped balloon comprises a hollow structure, and the stepped balloon after being filled forms a left atrial appendage orifice occlusion portion and a left atrial anchor portion; a diameter of the left atrial appendage orifice occlusion portion is larger than a left atrial appendage orifice; the left atrial appendage orifice occlusion portion is configured to completely fill and occlude the left atrial appendage orifice; a diameter of the left atrial anchor portion is larger than the diameter of the left atrial appendage orifice occlusion portion; the left atrial anchor portion is configured to be clamped on a left atrial wall of the left atrial appendage orifice to prevent the stepped balloon from sliding into the left atrial appendage; and a balloon filling inlet is disposed on a surface of the left atrial anchor portion, and the balloon filling inlet is configured to inject a liquid into the stepped balloon; a movable cover membrane is disposed on the surface of the left atrial anchor portion; and the movable cover membrane is configured to seal a surface of the stepped balloon when in closed position; a penetrating passage is disposed in the stepped balloon; a side of the occlusion disc is provided with a connecting column, wherein the side of the occlusion disc is configured to contact the left atrial appendage; the stepped balloon and the occlusion disc are configured to be fixed to each other by an extension connection of the penetrating passage and the connecting column.