In order to explore the clinical efficacy of renal unit preserving surgery for small kidney cancer, we summarized the clinical data of 47 patients who underwent renal unit preserving small nephrectomy from July 2005 to December 2007, which are reported below. Object and method 1. Clinical data There were 47 patients in this group, 31 males and 16 females. Their ages ranged from 26 to 73 years old, with an average of 48 years old. There were 27 cases on the left side, 19 cases on the right side, and 1 case on both sides. The tumors were located in the upper pole of the kidney in 12 cases, the middle of the kidney in 14 cases, and the lower pole of the kidney in 21 cases. The tumor diameters ranged from 0.8 to 3.0 cm, with an average of 2.3 cm. 38 cases were clear cell carcinoma, 6 cases were suspicious cell carcinoma, 2 cases were papillary renal cell carcinoma, and 1 case was cystic renal carcinoma. All cases belonged to T1aN0M0. 43 cases were asymptomatic, mainly due to physical examination, 1 case of hypothermia and 3 cases of hypertension. Isolated kidney was found in 2 cases. There were 7 cases of contralateral renal co-morbidities, including 2 cases of diabetic nephropathy and 5 cases of renal calculi. 2.Surgical method: General anesthesia with tracheal intubation, incision under the 12-rib margin, freeing the kidney, revealing the renal artery and blocking it, cooling the perinephric ice water, circumferential incision along the circumference of the tumor parenchyma with a small circular knife at 1 cm from the normal renal parenchyma, and then blunt separation with the knife handle to the base of the tumor, plucking out the tumor and some of the surrounding normal renal tissues, and removing the perinephric fat around the exophytic tumor together, and in case of If the renal pelvis is destroyed, it will be closed with absorbable sutures. The renal wound was covered with hemostatic gauze and sprayed with bioprotein gel, and the renal wound was closed with multiple “8” sutures with liver stitches. The blocking time ranged from 12 to 25 min, with an average of 17 min. Results All 47 procedures were successful. Intraoperative bleeding ranged from 100 to 350 ml, with a mean of (224 ± 65) ml, and no blood was transfused. There were no postoperative complications such as late bleeding, urinary leakage, or renal insufficiency. There were 45 cases with postoperative follow-up and 2 cases with loss of follow-up. 7 to 36 months of follow-up, mean 22 months, and no tumor recurrence. Discussion With the great progress of medical imaging, the detection rate of small renal cancer less than 3 cm in diameter has been increasing. Because most small kidney cancers are less malignant, there is no significant difference in efficacy between nephron-sparing surgery (NSS), which preserves the kidney unit, and radical kidney cancer surgery, and the latter needs to face the risk of isolated kidney and reappearance of tumor in the contralateral kidney, so NSS is gradually becoming the preferred treatment option for small kidney cancer. 1. NSS is more advantageous in those with lesions in the contralateral kidney, such as urolithiasis, hydronephrosis and diabetes. The main risk of NSS is the local recurrence of tumor after surgery, so the determination of surgical margins becomes critical. The ideal surgical approach should be intraoperative serial frozen sections to determine the presence of tumor remnants, but this may lead to prolonged renal ischemia and is less feasible in clinical practice. In addition, some studies have shown that the positive rate of intraoperative frozen section is extremely low, so the latest guidelines of the Chinese Society of Urology also suggest that intraoperative frozen pathological examination of tumor margins is not necessary. Most scholars at home and abroad believe that the incision margin of kidney preservation surgery should include 1 cm of normal kidney tissue outside the tumor, and that simple enucleation of kidney tumor is not appropriate. It is very important to adopt appropriate methods to protect renal function during surgery. Renal function impairment is related to the intraoperative blocking modality and the duration of thermal ischemia. Compared to intraoperative hemostasis with hand compression and complete renal tip block, renal artery block alone is the least damaging to the kidney 3,. In our group, the renal artery was easily found by dorsal freeing of the kidney from outside the perinephric fascia, and ice was placed to cool the perinephric area after blocking it, which can effectively protect renal function. In case of intraoperative destruction of the collecting system, absorbable sutures were given, and generally no pelvic drains were left in place. If the renal wound had obvious vascular dissection, absorbable sutures were given, and the wound was covered with hemostatic gauze and sprayed with protein gel and then closed with liver stitches, which can effectively prevent postoperative bleeding and urinary leakage. The combination of B-ultrasound and CT scan can effectively detect kidney cancer. Urine routine, kidney function, B-ultrasound, CT and chest X-ray should be checked every 3 months within 1 year after surgery, every 6 months after 1 year, and once a year for 2-5 years.