Limited endoscopic sphincterotomy with balloon dilation（ESBD）is a promising technique in treating common bile duct stones. It had the similar success rate of stone extraction, but its incidence of complications remained uncertain. However, there is no clinical evidence and guideline to define the optimal duration of balloon dilation so far. So we designed a prospective randomized trial to compare the effect of three different duration of balloon dilation during ESBD so that we can find the optimal duration of the balloon dilation.