Abstract: Objective To report a rare case of retroperitoneum unicentric Castleman disease（CD） and our clinical experience in its diagnosis and treatment. Methods Epidemic features,clinical and pathological typing,clinical manifestations,diagnosis,treatment and prognosis of the case were retrospectively analyzed based on the literature review. Results The patient was a 21-years old female student.She was accidentally found to have an abdominal mass with no symptoms and signs.CT revealed a mass in her upper abdomen with a clear margin and rich blood supply measuring 8.0cm×7.0cm×7.7cm.The tumor was found to be originated from the retroperitoneam during operation,which was pathologically diagnosed as a hyaline vascular（HV） CD and finally as a retroperitoneum unicentric CD according to its clinical manifestations.The prognosis of the patient was good during the follow-up. Conclusion CD is a rare lymph-proliferative and occupying abdominal disease.The prognosis of unicentric CD is good after radical surgery and the patients should be regularly followed up,while that of multicentric CD is poor and the patients should undergo chemotherapy and immune therapy.