Libman-Sacks endocarditis, characterized by verrucous vegetations formation, is a typical cardiac manifestation of autoimmune diseases such as systemic lupus erythematosus (SLE) and antiphospholipid syndrome (APS). Although typically mild and asymptomatic, Libman-Sacks endocarditis can lead to serious complications, including thromboembolic events, superimposed bacterial endocarditis, and severe valvular regurgitation and/or stenosis, and valve surgery may be required. Here, we report a case of mitral valve repair for a large Libman-Sacks vegetation in a 29-year-old woman with a history of APS with cerebral infarction. Transesophageal echocardiography (TEE) demonstrated an isolated large mobile vegetation on the atrial side of posterior mitral valve leaflet, with severe mitral regurgitation. Next, we organized a multidisciplinary team meeting to better evaluate the case before performing the surgery. To prevent further thromboembolic events, and due to the insufficiency of the mitral valve, the patient was accepted for mitral valve surgery, and she was discharged uneventfully 10 days after successful surgery. She was managed with long-term anticoagulation medicine after surgery and followed up for 2 years with no complications. The present case showed mitral repair is feasible and effective in young female patients of child-bearing age, and the lesion only localized mitral valve abnormalities caused by Libman-Sacks endocarditis.