Right atrial appendage aneurysms (RAAAs) are extremely rare in cardiac anomaly. According to the literature, no more than 25 cases have been reported so far, among which only 3 cases were children. Here, we reported an infant with a giant RAAA and severe symptoms. The RAAA was diagnosed by echocardiography and surgically resected under cardiopulmonary bypass. The role of transesophageal echocardiography was very important during the aneurysm resection surgery, which helped surgeons to plan surgical procedures during the surgery and evaluate the surgical effect postoperatively.