Gallstone disease is a very common disease identity in the world. Migration of stones from gallbladder to common bile duct (CBD), causing CBD stones (choledocholithiasis), occurs in up to 22% of cases. Traditionally, choledocholithiasis can be managed by therapeutic endoscopic retrograde cholangiopancreatography (ERCP) with interval cholecystectomy in 85% of patients. In around 15% of the patients, the clearance of choledocholithiasis cannot be effectively achieved with standard ERCP (difficult choledocholithiasis). As recommended by European Society of Gastrointestinal Endoscopy guideline, difficult choledocholithiasis can be managed by either endoscopic or surgical approaches. Clinical evidences by meta-analyses comparing endoscopic with surgical approaches are conflicting. Considering the timing of cholecystectomy to eliminate the pathological source of CBD stone, one-stage laparoscopic CBD exploration LCBDE plus laparoscopic cholecystectomy LC is an attractive approach. Although one-stage laparoscopic approach is associated with higher stone clearance rate (up to 96%) than traditional two-stage endo-laparoscopic approach (preoperative ERCP and LC), postoperative complication rate is substantial (up to 17%). Among those complications, postoperative bile leak is likely related to laparoscopic instrumental limitations in LCBDE. With advancement of da Vinci robotic system, there are 3-dimensional dual cameras providing high-quality intraoperative view and 7-degree of freedom of robotic instruments. The system is able to cope with complex hepatobiliary surgical procedure, including robotic CBD exploration (RCBDE). Theoretically, postoperative bile leak following RCBDE is lower than that of LCBDE. Hence, one-stage RCBDE plus robotic cholecystectomy RC could become a new standard of treatment for difficult choledocholithiasis. Up till now, only case series have reported the safety and efficacy of RCBDE. There is, however, no prospective randomized trial comparing one-stage RCBDE and RC with traditional two-stage endo-laparoscopic approach (preoperative ERCP and interval LC) for difficult choledocholithiasis, in terms of stone clearance rate and procedure-related complications. The investigators thus propose a single-center randomized trial on this issue. 90 patients (45 patients in each arm) with difficult choledocholithiasis will be randomized to definitive treatment by either one-stage robotic approach or two-stage endo-laparoscopic approach. The primary outcome is the stone clearance rate. The secondary outcomes include treatment related morbidity, hospital mortality, and hospital stay. This will be the first randomized trial in the world evaluating the efficacy of the novel one-stage robotic approach for difficult choledocholithiasis, and it will certainly add level 1 evidence to change the management algorithm for choledochothiliasis.