1,Laparoscope Sub-total Colectomy： After the entire colon mobilization,the ileum is resected at 10cm from ileocecum and 10-15cm colon up to peritoneal reflection is reserved. The ileocolic artery should be reserved carefully.2, Intestinal tract reconstruction: The terminal ileum is turned over 180°in anti-clockwise direction along the superior mesenteric vein long axis. To avoid the small mesenteric torsion, we should turn the broken edge towards inside. The terminal ileum and 10-15cm colon anastomose in anti-peristaltic direction,the anastomotic length is 8-10 cm.3, Sewn the space between anastomotic Intestine and posterior peritoneum. A drain is placed in the abdominal cavity and another one is placed in anal canal.