Abstract： Objective To investigate the clinical effect of McDonald cervical cerclage and the affecting factors. Methods Between January 2002 to December 2013 in Peking University First Hospital we performed McDonald cervical cerclage for 116 single pregnant women. They were defined as the successful group who deliveried the live babies after 28 weeks after the cerclage and the failure group who deliveried in the second trimester. According to the surgical indications they were divided into preventive&nbsp;cerclage group and therapeutic cerclage group. Then we analyzed the curative effect and the affecting factors in the groups. Results (1) In the 116 cases, 12 cases (10.3%) failed, and 104 cases (89.7%) succeeded. In the successful group, 37 cases (35.6%,37/104) deliveried pretermly and 67 cases (64.4%) deliveried termly. And there were 56 cases of vaginal delivery (53.8%), and 48 cases (46.2%) of cesarean section. (2) Among the 116 cases, 48 cases (41.4%) were included in prophylactic cerclage group, the gestational age was (16.3± 2.2) weeks, 68 (58.6%) cases were included in therapeutic group, the gestational age was (24.0±2.2) weeks. The operation time was (22±9) minutes in preventive group and (24±13) minutes in therapeutic group,there was no statistical difference between the two groups (P>0.05). Live-birth rate between preventive cerclage group and therapeutic cerclage group was no statistically significant difference (P>0.05). The term birth rate (72.9%, 35/48) in preventive group was higher than that in therapeutic group (47.1%, 32/68), the difference was statistically significant (P<0.01). Neonatal hospitalization rate was lower in preventive group (14.6%, 7/48) than therapeutic group (36.8%, 25/68) , the difference was statistically significant (P< 0.01). (3) In the failure group placental pathology was examed in 7 cases. The placental tissue showed a large number of neutrophils infiltrating in 6 cases (6/7). In the successful group, 27 pregnant women deliveried between 28 to 33+6 weeks (26.0%,27/104), 10 pregnant women deliveried between 34 to 36+6 weeks 10 cases (9.6%, 10/104), 67 cases deliveried after 37 weeks (64.4%, 67/104). A lot of factors including maternal age, the previous cervix operation history, perioperative application of progesterone, operation time and preoperative invasive procedure were compared between the successful group and the failure group. Only maternal age and preoperative invasive proedcure were statistically significant (P<0.05) and the others had no statistical significance (P>0.05). (4) There were 68 cases in the therapeutic group, 7 cases failed, and 61 cases succeeded;the preoperative cervical os in failure group [ (21 ± 20) mm] was wider than that in successful group [(14±5) mm], the difference was statistically significant (P<0.05);and preoperative vaginal ultrasound measurement of cervical canal length were (18 ± 8) mm versus (19 ± 10) mm, there was no statistically significant difference (P>0.05). Conclusions The McDonald cervical cerclage for cervical incompetence is a simple, safe and high successful rate of intervention measures. The term labor rate of prophylactic cervical cerclage was higher than that of the therapeutic cerclage. Older maternal age and preoperative invasive procedure may be the risk factors for cerclage. The infection may play an important factor leading to the failure of McDonald cervical cerclage.