Preterm birth,occurring in 5% to 18% birth of births worldwide, is the main cause of neonatal death and other adverse outcomes. Many surviving preterm birth need to face lifelong disability, including learning disabilities, vision and hearing problems. Among them, 70% to 80% are spontaneous preterm births (SPB), and the remaining 20% to 30% are therapeutic preterm delivery. Progesterone is an important substance to maintain pregnancy. More and more evidences show that vaginal use of progesterone can prevent the occurrence of SPB. In 2020, the society of Obstetricians and Gynaecologists of Canada, SOGC) summarized the latest clinical research evidence of progesterone in the prevention of SPB, and provided clinical guidance and recommendations for the mechanism of action, the appropriate population, unsuitable population, dosage, timing and side effects of progesterone in the prevention of SPB. At the same time, the guideline compared progesterone therapy with cervical cerclage, vaginal pessary and bed rest to prevent SPB. This paper interpreted the main points of its recommendation in order to provide reference for medical workers in China. [ABSTRACT FROM AUTHOR]