Renal tumor surgery, on the one hand, emphasizes the complete removal of tumor and on the other hand, emphasizes the maximum protection of kidney function. However, for patients with isolated kidney (only one kidney), if a tumor occurs in the only remaining kidney, how to treat it becomes a huge problem for doctors and patients. If the treatment fails, once the tumor progresses or the whole kidney has to be removed, the patient will be dependent on dialysis treatment for the rest of his life. Usually, we choose partial nephrectomy or cryoablation of kidney tumor to destroy the tumor while preserving the kidney. It is important to mention that partial nephrectomy for this group of patients is a success and not a failure. We have recently encountered several patients with isolated kidney with renal tumor who have successfully undergone nephrectomy with kidney preservation. Today, we present a case in which the tumor shrank after receiving neoadjuvant targeted therapy and then successfully underwent partial nephrectomy. The patient’s renal function was well preserved by the surgery. The patient’s medical history is as follows: the patient underwent radical right kidney cancer 14 years ago due to right kidney tumor, postoperative pathology: clear cell carcinoma, tumor 8*9cm. postoperative routine follow-up review did not show any abnormality. 2015.6.18 review CT showed: left kidney lower pole mass slightly high density shadow, size 41*42mm, tumor adjacent to ureter and lower pole blood vessels, part of the area adjacent to the renal pelvis. The CT of chest did not show any abnormality. At that time, the abdominal CT was as follows: Considering the patient’s postoperative history of renal cancer, at present, a new tumor was found in the isolated kidney, and the nature of primary or metastasis was to be determined, while no metastases from other sites were found. Therefore, after communicating with the patient and family, considering the objective risks of surgery (damage to ureter or possibility of intraoperative haemorrhage), it was decided to first neoadjuvant targeted therapy and try to perform partial nephrectomy after further tumour reduction. The patient started oral doxorubicin 2 capsules in the morning and 1 capsule in the evening on 23.6.2015, the main adverse effects were hand-foot syndrome, hair loss and diarrhea, which were poorly tolerated by the patient. 2015.7.29 review abdominal MRI: left kidney lower pole nodule, about 29mm tumor, smaller than before. The post-treatment abdominal MRI was as follows: 2015.8.11 Left kidney preserved renal unit surgery was performed, and cold ischemic technique was used to further protect the kidney during the operation, which was successful and successfully removed the renal tumor and preserved the majority of normal renal tissue. This patient had creatinine CRE(creatinine):103umol/l in July and creatinine CRE(creatinine):112umol/l on the first postoperative day, and the subsequent creatinine changes are yet to be observed in the long term. Complete postoperative pathology report: Specimen type: (left) partial nephrectomy specimen; tumor site: /; tumor section: grayish yellowish grayish white color; tumor size: 3.8*3.6*3cm; satellite foci: (-); histological type: clear cell renal cell carcinoma; cancerous tissue necrosis: (-); Furhman nuclear grade: grade 3; lymph node metastasis: ( / ) (number of metastases / number of lymph nodes). Fibrous perineural invasion: (+); perirenal fat invasion: (-); specimen margin: (-); ureteral margin: /; intraventricular carcinoma thrombus: (-); nerve invasion: (-); renal vein tumor thrombus/invasion: /; adrenal gland invasion/metastasis: /.