Abstract: The pessary has emerged as a possible treatment for the prevention of preterm birth，the exact mechanism in reducing the likelihood of preterm birth is unknown，one hypothese suggested that the pessary encompasses the cervix and changes the uterocervical angle. Different models of pessaries are used to prevent preterm birth and among them the most widely used is Arabin pessary. Its dome-like design resembled the vaginal fornix，surrounded the cervix as close as possible to internal. The pessary size should be choiced according to the clinical situation and cervical morphology. In recent years，many studies have shown that the use of pessary can significantly prolong the delivery gestational age, reduce the rate of preterm birth and poor perinatal outcome，especially in high risk population of women such as cervical incompetence and twins pregnancy. Compared with the other methods，like the use of progesterone in vagina and cervical cerclage, there′s no significant side effects have been reported，the most common complaint is an increase in vaginal discharge, besides，cervical pessary can be inserted and removed easily without the need for anesthesia and is noninvasive and inexpensive. However，due to the lack of available high quality randomized controlled trials，the benefit of the cervical pessary could not be confirmed and further research is urgently needed.

Key words: Pessaries, Premature birth, Uterine cervical incompetence, Twins