Objective To explore the influence of different common bile duct diameters （CBDD） on the clinical efficacy， safety， and postoperative biliary tract-related complications in patients with common bile duct stones who receive laparoscopic common bile duct exploration （LCBDE） combined with primary suture， aiming to provide a reference basis for the selection of clinical surgical indications. Methods The clinical and follow-up data of 103 patients with common bile duct stones who were treated with LCBDE combined with primary suture were retrospectively analyzed in the Department of Hepatobiliary Surgery of the Third Affiliated Hospital of Guizhou Medical University from March 2022 to September 2025. Based on the outer diameter of the common bile duct measured by preoperative magnetic resonance imaging （MRI） and intraoperative measurement， the patients were divided into the small-diameter group （Group A， 0.6 cm ≤ CBDD < 1.0 cm， n = 42） and the dilation group （Group B， CBDD ≥ 1.0 cm， n = 61）. The baseline characteristics， surgery-related detailed indicators， postoperative dynamic recovery of liver function， and incidence rates of complications were compared and analyzed between the two groups of patients. Results There were no statistically significant differences in preoperative baseline data between the two groups （P > 0.05）. In comparison with group B， group A had a longer surgical time and a longer postoperative hospital stay （P < 0.05）， as well as a shorter common bile duct incision length （P < 0.05）. The levels of alanine aminotransferase （ALT） and total bilirubin （TBIL） on the 1st day after surgery （POD1） and the 3rd day after surgery （POD3） in both groups decreased significantly compared to the preoperative levels （P < 0.05）， and there were no statistically significant differences between the groups at the same time-points （P > 0.05）. The overall incidence rate of postoperative complications showed no statistically significant difference between the groups （P > 0.05）. Specifically， group A had 3 cases （7.14%） of bile leakage， whereas group B had 2 cases （3.28%）. These 5 cases were classified as ISGLS grade A bile leakage and resolved with conservative treatment， with no statistically significant difference between the groups （P > 0.05）. Conclusions CBDD < 1.0 cm is not an absolute contraindication for primary suture. Although a small-diameter bile duct increases the difficulty of surgery， prolongs the surgical time， and extends the hospital stay， it does not impede the rapid recovery of postoperative liver function and does not significantly increase the risk of complications such as severe bile leakage， with definite clinical efficacy.