Primary malignant fibrous histiocytoma of the renal pelvis is extremely rare. This article reports a pathologically confirmed case. Surgery is the main treatment for this disease. Chemotherapy and radiotherapy have been reported to be ineffective. It is difficult to differentiate it from urothelial tumor of the renal pelvis and renal cell carcinoma by preoperative laboratory and radiological evaluation. Immunohistochemical study is helpful in confirming the diagnosis of the disease. This report discusses the clinical manifestations, pathohistological characteristics, treatment, and prognosis of the case reported.