A 5-year-old and 3-month-old child with Williams syndrome was found to have a heart murmur during a physical examination. An echocardiogram indicated supravalvular aortic stenosis. The child was scheduled to undergo corrective surgery for supravalvular aortic stenosis under general anesthesia. Children with Williams syndrome often have supravalvular aortic stenosis and coronary artery disease. Supravalvular aortic stenosis usually causes increased left ventricular afterload and left ventricular centripetal hypertrophy. Coronary artery disease causes poor myocardial perfusion and myocardial ischemia, which significantly increases the risk of arrhythmias and cardiac arrest. Anesthetic management for these children should maintain adequate circulatory volume and good coronary artery perfusion, avoid myocardial oxygen consumption increase, and prevent the occurrence of perioperative hypotension.