To evaluate the impact of transanal endoscopic microsurgery (TEM) on postoperative anal function and quality of life in patients with benign rectal tumor and early rectal cancer. Clinical data of 50 patients with rectal adenoma and early rectal cancer undergoing transanal endoscopic microsurgery in our hospital from October 2008 to June 2013 were retrospectively analyzed. Anorectal manometry, endorectal ultrasonography (ERUS), the fecal incontinence severity index (FISI), and the physical and mental health status scores (SF-36) were used to evaluate preoperative and postoperative anorectal function and quality of life. Anorectal manometry indicated anal resting pressure (ARP), maximum squeeze pressure (MSP), rectal volume at sensory threshold(RVST), maximum tolerable volume(MTV) decreased significantly at the first month after surgery (P<0.05). MSP returned to preoperative level at the 3rd month (P>0.05). ARP and MTV returned to normal values at the 6th month (P>0.05). RVST returned to normal values at the 9th month (P>0.05). Recto-anal inhibitory reflex(RAIR) was absent in 1 (2%) patient preoperatively and in 30(60%), 18(36%), 7(14%), 2(4%) at the 1st, 3rd, 6th, 9th months after surgery respectively. ERUS showed similar width and thickness of internal sphincter at 1st and 6th month after surgery compared with preoperative measures (P>0.05). Six months after surgery, the mean FISI score decreased(preoperative vs postoperative:8.5 vs 5.8, P<0.05), suggesting an improvement in fecal continence. However, the overall quality of life did not danger significantly after surgery(P>0.05). TEM has little impact on anorectal anatomic structure. Anal function may be compromised in the short-term, however the vast majority of patients recover completely after 6-9 months. TEM is a safe, effective and minimally invasive surgery.