The present teachings provide methods for resizing, reducing, and closing left atrial appendage. Specifically, a percutaneous trans-septal access is first established from outside the body to a patient's LAA. At least two tissue anchors are then implanted inside the LAA chamber and along the tissue wall. At least one anchor is implanted near the opening of the LAA camber. Both tissue anchors are pulled together so that the wall of the LAA chamber collapse. The LAA chamber is therefore resized, reduced, and/or closed off completely. This closure method and system could be used alone in closing LAA chamber. This closure method and system could also be used in addition to other treatment mechanisms, such as filling the LAA chamber with space-filling material, then closing off its opening.