Object: To investigate the feasibility and safety of hysteroscopic surgery for diagnosis and treatment of complex uterine cavity diseases under the monitor of 5mm-mini-incision micro-single-hole laparoscopic surgery. Methods: A retrospective analysis of 15 patients with complex uterine cavity diseases undergoing hysteroscopic surgery underwent 5mm-mini-incision micro-single-hole laparoscopic surgery was performed in the Department of Obstetrics and Gynecology, the Affiliated Changzhou NO. 2 People's Hospital of Nanjing Medical University from April 2018 to March 2019. Among them, 8 cases were intrauterine adhesion, 3 cases were uterine submucosal fibroid, 3 cases were uterine septum, 1 case was post-cesarean scar pregnancy, ages from 23 to 45 years old, BMI 17.65-25.48kg/m 2 . The operation was performed through a 5mm-mini-incision from the midline of the umbilicus. The 40/50 small abdominal retractor was used to expand the incision approach. A 3-mm small lens (A cystoscope or a hysteroscope was used for some patients) was placed into the single-port approach to perform the laparoscopic surgery; hysteroscopic surgery was performed by hysteroscopy through the cervix. Results: All the 15 patients were successfully operated. One patient with severe intrauterine adhesion had uterine perforation during operation. The uterus was repaired and sutured under micro-single-hole laparoscopy perfectly. No other channels were added during operation, and no laparotomy was performed. The operation time was 20-125 min, in which the surgical path establishment time was 5-10 min, the umbilical reconstruction time was 3-5 min; the intraoperative blood loss was 5-10 ml, and the postoperative hospital stay was 3-7 days. The postoperative umbilical incision healed well, and there was no surgical scar in the abdomen after surgery. No postoperative umbilical hernia and other serious complications occurred. Conclusion: Under the premise of mature umbilical single-port laparoscopy, it is safe and effective to use 5mm-mini-incision micro-single-hole laparoscopic surgery as a monitor during hysteroscopy for the diagnosis and treatment of complex uterine cavity diseases. It will achieve a better cosmetic result than traditional laparoscopy.