Objective:To study the effect of cervical canal mucosa dng excision on cervical columnar eversion in Loop electrosurgical excision procedure(LEEP).Methods:A prospective randomized control trail was performed in 125 cervical intraepithelial neoplasia(CIN)patients.Cervix and cervical canal were conically excised with triangle electrode in 62 patients in the control group;in the study group,a small ring electrode was put into the cervical canal and the cervical canal mucosa was excised about 0.5～0.8cm,after excision as the control group.Follow-up was performed postoperatively in 1,3,6 months respectively.The operation time,the bleeding volume,the rate of cervical columnar eversion and cervical adhesion or stenosis were compared between the two groups.Results:The rate of cervical columnar eversion in the study group (1/63,1.59%)was lower than that in the control group(9/62,14.52%).There was significantly statistical difference between them(P=0.008).There was no statistical differences between them in the operation time,the bleeding volume,and the rate of cervical adhesion or stenosis (P>0.05).Conclusions:The cervical canal mucosa ring excision in LEEP can effectively prevent postoperative cervical columnar eversion.