Objective To introduce the experience of laparoscopy and ultrasonic knife in long-segment congenital megacolon surgery, and to explore the prospect of the application of laparoscopy and ultrasonic knife in long-segment congenital megacolon surgery. Methods Seven cases of long-segment congenital megacolon were operated by general anesthesia with tracheal intubation and three holes in the abdominal wall for accessing the scope and operating instruments. The diseased colon and proximal rectal mesentery were freed to the pelvic floor with an ultrasonic knife under direct laparoscopic view. The rectal mucosa was incised at 5 mm on the dentate line of the anus, dragged down and upward to separate the rectal mucosa to the peritoneal reflex, cut the rectal muscle sheath, incised the retained posterior sheath of the rectal muscle sheath, separated the rectum to the intra-abdominal rectum free, and dragged out the normal colon to anastomose with the incised edge of the rectal mucosa on the dentate line. The result was that the average operation time was 186 min, and the patient was able to ventilate and defecate 24 h after surgery. Follow-up results were good. Conclusion Laparoscopy with ultrasonic knife for radical surgery of megacolon is less invasive, safe and effective, and has good application prospects.