The thymolipoma is rather rare benign tumor of the thymus. One case of huge thymolipoma, seen in a 11-year-old boy, is presented. It is about 2.16kg. He had some chest discomfort. The chest film showed homogeneous haziness fills the left hemithorax, On chest CT scan, multiple small amorphous soft tissue densities were recognized as islands within a large fatty mass. Tumor resection was performed through left anterolateral thoracotomy. The mass was yellowish soft, measured 29x19Xllcm, 12X7.5x3.5cm, 7.0X3.0X1.0cm. Microscopically, the tumor was comprised of abundant mature adipose tissue and normal thymic tissue.