Objective To investigate the effects of cervix cerclage in pregnant period with cervical incompetence. Methods 40 cases of cervical incompetence during January 2010-June 2013 in our Hospital.They were treated by cervix cerclage at 12-16 weeks of pregnancy on the basis of rest in bed and the treatment of tocolysis. Results The operation were successful and without complication in 40 patients. The successful rate was 86.4% in the patients whose cervix length 15 mm, 20 mm before cerclage and 44.4% in whose cervix length ≤15 mm. The ratio of vaginitis after operation is significantly lower in the patients who's successful in the operation(P0.05). Conclusion The outcome of pregnancy significantly improved by cervix cerclage in pregnant period. Length of cervix and vaginitis after operation are the main factors that influence the success of operation. To the patients whose cervixlength≤15 mm or with vaginitis, cervix cerclage by laparoscopy or vaginal pre pregnancy is appropriate.Prevention of infection can improve the success rate of cervix cerclage.