An internal tube, called a T-tube, is placed inside the common bile duct to remove the stone. Due to the better histocompatibility of the tube nowadays, the extraction time for the T-shaped drainage tube in clinical practice is now generally until 6-8 weeks or more after surgery, and a T-tube imaging must be done before extraction to find out whether there are residual stones or other lesions in the bile ducts inside and outside the liver, as follows: 1. If there is no problem, it can be extracted after 6-8 weeks; 2. If the imaging reveals that the bile duct has stenosis or residual stones, the T tube If there is any suspicion of residual stones in the bile duct, it can be removed only after 6-8 weeks of postoperative choledochoscopy and then another imaging, which reveals that the bile duct is free of other lesions.