Abstract: Objective To study CT diagnosis and differential diagnosis of the cystic lesions in abdomen in children. Methods 16 cases of the cystic lesions in abdomen were confirmed by surgery and histopathology.To analyze CT features of every lesions. Results 3 cases of the cystic lesions in abdominal cavity include 2 cases of the giant cystic lesions of the omentum majus,1 mesenteric cystis.13cases of retroperitoneal cystis lesions include 7 choledochoceles,2 inflammatory cyst,1 cystic teratoma, 3 giant hydronephrosis. Conclusion CT diagnosis of the cystic lesions in abdomen in children is ease when lesions are minor. CT differential diagnosis is difficult when cystic lesions in abdomen are the giant.