Objective To evaluate the safety and ascendancy of small caliber stapler application for anterior resection in ultra-low rectal cancer with anal sphincter preservation. Methods A retrospective analysis of the data of 60 cases of ultra-low rectal cancer treated by anterior resection with anal sphincter preservation by double stapling technique according to TME principle between June 2006 and June 2009 were undertaken. The 60 patients were divided into two groups, each group included 30 cases. One group adopted 33 mm stapler and another group adopted 29 mm stapler, and then the profiles of medi-operation, post-operation, and prognosis were assessed. Results Time of simple anastomose in operation was (9.0±3.3) min in 33 mm stapler group and (6.0±2.6) min in 29 mm stapler group, and there was significant difference between them (P=0.022 5). There were 6 cases needed to be restored because of lesion during operation or dys-anastomosis in 33 mm stapler group, while 2 cases in 29 mm stapler group, there was significant difference between them (P=0.030 1). No significant differences were observed between the two groups in terms of the time for operation, leakage, bleeding, stenosis, anastomotic recurrence, and fecal incontinence after operation or length of stay. Conclusion The application of 29 mm stapler not only can shorten time for anastomose and step down the degree of difficulty, but also dosen’t increase stenostomia and other complications.