Objective:To investigate the anatomic foundation of modified rehbein's operation and define a standard procedure.Methods:We retrospectively analyzed 49 cases of Rehbein's operation and summerized our experience.Results:We dissected the posterior wall of rectum from the retroperitoneum beside the Douglas's pouch downward to the anus levator muscle,laterally to the middle part of retal lateral ligment.Then incised the posterior wall to the level 0.5～0.8cm above the dental line.Finally we anastomosed the proximal and distal part of rectum delicately.98.0% of these cases have normal defectation function during follow up.Conclusion:With standard procedure,this operation can be performed smoothly,and patients survive conveniently with undisturbed defectation reflex.