To discuss the feasibility, safety, and effectiveness of off-clamp robotic partial nephrectomy via retroperitoneal approach and provide data for evidence based medicine in the surgical treatment of renal tumor.The clinical data was documented and compared between robotic retroperitoneal partial nephrectomy with and without hilar occlusion (clamp group and off-clamp group) performed between January 1, 2015 and December 31, 2017.Six-months post-operative renal function was superior in the off-clamp group compared with clamp group, while long-term results remained to be elucidated. No significant difference in post-operative hospital stay was found between the 2 groups. Estimated blood loss in off-clamp group was significantly higher than clamp group, while no significant difference was found in transfusion rate.Off-clamp robotic partial nephrectomy via retroperitoneal approach is a safe and effective technique for the removal of renal tumor while the indication of surgery is strictly limited to small (<4 cm) and exophytic renal tumor.