Anal preservation surgery for low rectal cancer is the most difficult part of surgical treatment. The use of trans-sphincteric gap proctocolectomy is the most difficult type of anus-preserving surgery and is performed in only a few large hospitals at home and abroad. In this surgery, the abdominal group of surgeons free the sigmoid colon and rectum to the pelvic floor, and the perineal group of surgeons free the perineum from the dentate line (or white line) through the anal sphincter gap to the pelvic floor. After excision of the specimen, the perineal group surgeons make anastomosis between the colon and the anal sphincter. The possibility of postoperative anastomotic fistula is higher, and a protective ileostomy is routinely made intraoperatively, and the stoma is returned after the colon and anal canal have healed without risk (usually a 3-month interval is needed for the second operation). Even if a protective ileostomy is done for trans-sphincteric rectal resection, anastomotic fistula still occurs in 10-20% of patients after surgery. Once an anastomotic fistula occurs, the patient’s perineal anus will become a permanent false anus due to the possible disconnection of the colon from the continuity of the anal canal, the proliferation of surrounding scar tissue, and the narrowing of the anastomosis, making the ileostomy irreducible in some patients. Dr. Ping Huang has gained mature experience in modifying the trans-sphincteric gap rectal resection. In general, Dr. Huang Ping uses laparoscopic techniques to free not only the sigmoid colon and rectum down to the pelvic floor, but also the left hemicolectomy upward, which is twice the scope of normal colorectal cancer surgery, and can be called “top of the line”. After removing the specimen from the anus, the colon is pulled out 3-5 cm through the anal canal, and then the excess colon outside the anus is removed after the pulled colon and the anal canal are firmly healed. Dr. Huang Ping’s modified laparoscopic trans-sphincter gap rectal cancer anal preservation surgery is the first of its kind in China and abroad: (1) not only there is no incision in the abdomen. ②It also avoids making a protective ileostomy in the patient’s abdomen. The modified method avoids the possibility of anastomotic fistula and enables the patient to have good postoperative anal control of defecation. (3) In addition, the modified surgery does not use anastomotic anastomosis, which saves about RMB 5,000 to 10,000 yuan. The modified surgery is beneficial to patients with rectal cancer, and is suitable for the radical anal preservation of rectal choroidal adenomas 3-5 cm from the anus or rectal cancer (T1-T2) located within the muscular layer of the rectal wall, and also for rectal cancer (T1-T3) located 5-6 cm from the anus and within the rectal mesentery.