Abstract: At present, the standard left atrial appendage occlusion procedure mainly involves two-dimensional imaging methods such as X-ray fluoroscopy and transesophageal echocardiography to guide the operation, which will lead to underestimation of the three dimensional structure of the left atrial appendage and the surrounding tissue, thus adversely affects the surgery. To solve this problem, a surgery assist system for left atrial appendage occlusion based on preoperative cardiac CT images is developed. The proposed system realizes the left atrial appendage parameter measurement based on cardiac CT image, and realizes the calculation of optimal delivery sheath trajectory and three-dimensional simulation of the delivery sheath movement on the basis of a novel delivery sheath trajectory model. The system is expected to provide precise guidance for left atrial appendage occlusion, improve the success rate and safety of the operation, and at the same time help reduce the difficulty of learning the operation, and facilitate the promotion of left atrial appendage occlusion.