Renal eosinophilic tumor (oncocytoma) is a rare benign renal parenchymal tumor, which was first reported by Zippel in 1942, and was only taken seriously when Klein and Valensi reported 13 cases and discussed them in detail in 1976. However, its pathogenesis is still unknown. Renal eosinophilic tumor can occur in all age groups, but it is more common in middle-aged and old people over 60 years old, mostly occurs unilaterally, bilateral lesions account for about 6%; more men than women, male to female ratio 3.1:l. Most patients have no clinical symptoms, a few may have lumbago, hematuria or abdominal mass, and physical examination is mostly without positive signs. Most of the patients have no clinical symptoms, a few may have lumbar pain, hematuria or abdominal masses, and no positive signs on physical examination. It is generally believed that the scar is due to slow growth and long-term ischemia, so the larger the tumor is, the higher its incidence. Recently, MRI has been found to have unique value in the diagnosis of renal eosinophilic tumor, which can show intact tumor envelope, central stellate scar, and enhancement in T1 and T2 phases, which can suggest the diagnosis. The literature reports that its MRI T1-weighted presentation is low-intensity and homogeneous, and the central region stellate scar image may be clearer and more typical than CT. Therefore, stellate scar in the central region is considered to be a characteristic imaging manifestation of renal eosinophilic tumor. The pathological histology of renal eosinophilic tumor has certain characteristics. The tumor is well-defined by the naked eye, and most of them have envelope, and the tumor mostly does not break through the envelope. The surface of the tumor is mostly light brown or brown, with uniform texture, no hemorrhagic necrosis and multivessel phenomenon. The tumor is composed of typical renal eosinophils with consistent cell morphology, nest-like or adenoidal arrangement, generally without papillary structure, rare nuclear anisotropy and splitting phase, and no clear cells or necrotic foci. A distinctive feature of renal eosinophilic tumors observed by electron microscopy is the large number of mitochondria clustered in the cell plasma, which are larger and more numerous than in other renal tumors. Immunohistochemistry usually shows Cytokeratin (+), EMA (+), and Vimentin (-). The lack of symptoms and signs characteristic of renal eosinophilic tumor, and the uncertainty and non-specificity in imaging make the preoperative diagnosis more difficult, and currently, we mainly rely on pathological examination to clarify the diagnosis. In this case, because the tumor was close to the renal hilum, and the preoperative imaging data did not show any characteristic manifestations such as stellate scar in the central part of the tumor, and the clinical management of renal parenchymal lesions has always put renal cancer in the first place unless there is data proving that it is really a benign lesion, radical resection of the affected kidney was performed. Many foreign data show that renal pheochromocytoma is a benign tumor with slow growth and good postoperative prognosis, so renal preservation surgery should be performed, but attention should be paid to the possibility of complicating renal malignancy. Therefore, if the preoperative imaging suggests the possibility of this disease, especially if the tumor is located in one pole of the kidney, tumor removal or partial nephrectomy can be performed first, and intraoperative tumor and tissues of the cut edge can be examined by frozen pathology to clarify the nature of the tumor before deciding whether to expand the scope of surgery to avoid unnecessary radical nephrectomy, which is especially important for patients with isolated kidney or contralateral renal dysfunction.