Retroperitoneal fibrosis (RPF) is a group of histopathies characterized by chronic nonspecific inflammation of retroperitoneal tissue, with insidious onset, mostly detected by unexplained hydronephrosis, and often leading to serious complications such as renal failure. 1.Symptoms: back pain, nausea, vomiting, hydronephrosis; concomitant symptoms: hypertension, hematuria, swelling of lower limbs, varicose veins of lower limbs. 2.Laboratory tests ESR and CRP are often used as indicators to evaluate disease activity and efficacy. 3.Imaging is an important tool to detect and diagnose RPF. (1) IVU and ultrasound: significant role in the detection of hydronephrosis and preliminary exclusion of stones and urological tumors, but the specificity and sensitivity of diagnosis of RPF is poor. (2) CT and MRI: the most reliable methods for the diagnosis of primary RPF, which appears on CT as a well-defined but irregularly shaped soft tissue mass located next to the spine, with the same density as the surrounding muscle, with the central part of the mass usually located at the bifurcation of the abdominal aorta and extending peripherally, extending forward to encircle the duodenum, pancreas, spleen, etc., and down to the sacrum; the enhancement of the soft tissue mass is related to the inflammatory stage of the lesion. The soft tissue masses are associated with the stage of inflammation. In the acute phase of inflammation, there is high enhancement, 20-60 HU, and in the late phase of inflammation, there is mild or no enhancement; CT can also provide useful information in differentiating between benign and malignant, with malignant RPF being larger and often encircling the unilateral ureter, while pushing the abdominal aorta and inferior vena cava forward away from the spine. MRI has a better soft tissue resolution and is also advantageous for the diagnosis of this disease. The differentiation between benign and malignant RPF should be combined with the patient’s history, laboratory tests, imaging performance and pathological biopsy. 4, treatment The principles of treatment for hydronephrosis due to RPF: first determine whether there is significant impairment of renal function, and if so, immediately decompress through percutaneous puncture nephrostomy or ureteral cannula, and then clarify whether there are secondary causes or some autoimmune diseases associated with it, and if so, perform targeted treatment. The decision is then made whether to further address the obstruction with medication or surgery: secondary RPF is mostly treated differently for the primary cause, and there is much controversy in the treatment of primary RPF. Pharmacological treatment is most often done with cortisol hormones, and more scholars suggest combining surgical management with medication for primary RPF temporary indwelling ureteral stent tube or nephrostomy tube + medication is now the more popular approach. Laparoscopic and robotic line release surgery for RPF has been used in clinical practice. In early or active stage of RPF, obstruction is more likely to be caused by edema and congestion of retroperitoneal masses compressing the surrounding organs, when temporary relief of obstruction by ureteral cannulation and simultaneous use of drugs to control inflammation and reduce edema may be the main treatment, while in late or chronic stage of RPF, the retroperitoneal lesions have become fibrotic and cannot be reversed by drug therapy, when ureteral release interperitoneal placement or long-term ureteral placement should be used as the main treatment.