Background Preterm birth is the main cause of child death under 5years of age.The incidence of twin pregnancies is less than 2%, but the incidence of preterm delivery is 50% and the risk of neonatal death is 5 times higher in twin pregnancies than in singleton pregnancies.However,there is still no consensus on the effect of cervical pessary on preventing preterm delivery, prolonging the pregnancy cycle, and improving maternal and infant outcomes in patients with twin pregnancies. Objectives To explore the effect of cervical pessary on the pregnancy outcome of unselected twin pregnancy patients. Search Strategy Up to July 2021,researchers searched PubMed, EMBASE, COCHRANE, Web of Science, Wanfang, Weipu, and CNKI databases for research. Selection Criteria Randomized controlled trials that compared cervical pessary with standard care (no pessary) or alternative interventions(conventional and standard treatment (e.g.Atoxiban therapy) or vaginal progesterone) in patients with twin pregnancies. Data Collection and Analysis Two authors（W-Y and M-D）independently extracted information related to the study characteristics and test results from each of the included literature, and used Revman 5.3 to analyze the data. Conclusion The cervical pessary can extend the gestational week of short-cervix twin pregnancy without clinical symptoms, reduce the premature birth rate before 34 weeks of gestation, improve pregnancy outcome, reduce neonatal mortality, reduce necrotizing enterocolitis incidence, neonatal sepsis incidence, and improve neonatal outcome.