The patient was found to have a “latent” tumor in the left kidney by ultrasound during the physical examination. In ultrasound and later CT scan, the tumor behaved differently from common kidney cancer – it was close to normal kidney structure in terms of echogenicity and density, therefore, it was indeed a “latent” tumor. The patient and his family strongly wished to preserve the left kidney while completely removing the tumor. We considered that the patient had a history of hypertension for nearly 10 years and the kidneys (including the right normal kidney) had some degree of hypertensive nephropathy. Therefore, it was decided to perform a minimally invasive surgery – laparoscopic partial nephrectomy (selective renal artery branch block type) – on the patient. The difficulty of the operation is mainly twofold: 1. The tumor is completely hidden inside the kidney and cannot be localized by the naked eye from the surface of the kidney. The diagnosis of this kind of kidney tumor, especially the resection operation, is the most severe challenge for the urologist. Therefore, we adopt laparoscopic ultrasound probe to perform intraoperative ultrasound localization and marking on the kidney surface, so as to accurately expose the “latent” tumor. 2. Normally, partial nephrectomy requires complete intraoperative blockage of the renal artery trunk to ensure almost no bleeding at the trauma surface during tumor removal, but the biggest problem with this approach is that the whole kidney (including normal kidney tissue) will face the possibility of ischemic injury leading to serious impairment of renal function. In order to minimize ischemic injury, we analyzed that the tumor was located on the dorsal side of the left kidney and the renal artery was divided into 3 branches earlier by preoperative vascular CT scan, and confirmed that the dorsal branch of the renal artery was the main blood supply vessel for the tumor and the dorsal kidney tissue by trial clamping; therefore, we did not block the main trunk of the renal artery but only blocked the dorsal branch of the renal artery to successfully complete the tumor resection and kidney suture, which achieved the goal of minimizing ischemic injury. Therefore, we successfully completed the tumor resection and kidney suture without blocking the main renal artery but only the dorsal branch of the renal artery, achieving the expected goal of minimizing ischemic injury.