The purpose of postoperative T-tube drainage for common bile duct stones is as follows: 1) to reduce pressure and biliary tract pressure; 2) to prevent biliary fistula in postoperative biliary incision; 3) to help biliary incision healing; 4) to facilitate the remission of inflammation in the duodenum, i.e., the lower duodenal papilla of the bile duct; 5) to help the remission of postoperative jaundice; 6) to facilitate the discharge of residual stones in the bile duct after surgery. After placement of the T-tube, as the T-tube can form a sinus tract after surgery, it facilitates postoperative bile duct or intrahepatic bile duct lithotripsy again or repeatedly through T-tube angiography or cholangioscopic operation via the T-tube sinus tract. T-tube drainage is also an effective way to treat biliary obstruction in certain patients with neoplastic disease of the lower biliary tract who are deprived of surgical opportunities.