The goal of this clinical trial is to investigate whether robot-assisted laparoscopic partial nephrectomy by extraperitoneal approach in the prone position had any advantages over the traditional lateral position. The main questions it aims to answer are: Is prone surgery safe and feasible, and what are the advantages over the traditional lateral position? Does surgery in the prone position have an impact on the patients\' prognosis? Researchers will compare prone position to lateral position to see if robot-assisted laparoscopic partial nephrectomy by extraperitoneal approach in the prone position has any advantages over the traditional lateral position and whether it has any significant effect on the prognosis of the patients. Participants will be randomly allocated 1:1 to two groups: prone position group and lateral position group. The enrolled patients will be underwent robotic-assisted laparoscopic partial nephrectomy via extraperitoneal approach according to the corresponding positions of their groups. Demographic indicators and perioperative-related indicators will be counted and recorded. CT or MRI and related biochemical examinations will be reviewed at 1 month, 3 months, 6 months and 1 year after surgery, and every 1 year thereafter. The similarities and differences of the indicators in different positions will be analysed, and subgroup analyses will be performed according to the corresponding results.