Objective To investigate the relationship between histological chorioamnionitis(HCA) and the outcome of preterm labor. Methods A total of 218 cases of premature delivery in the Department of Obstetrics and Gynecology of our hospital from January, 2015 to December, 2017 were divided into two groups according to the result of placenta pathological diagnosis. The observation group was diagnosed with histological chorioamnionitis by placenta pathology examination. The control group was not diagnosed with histological chorioamnionitis. The delivery gestational week, the rate of premature rupture of membranes, the rate of puerperal infection, the rate of postpartum hemorrhage, the rate of wound healing failure, the average body mass of newborn infants, the rate of early-onset sepsis, asphyxia, respiratory distress syndrome rate, pathological jaundice rate, neonatal mortality between the two groups were compared. And the impact of histological chorioamnionitis on the outcome of preterm labor was explored. Results The delivery gestational week of the observation group was (32. 0±1. 0) weeks, and the rate of postpartum hemorrhage, the rate of premature rupture of membranes, the rate of puerperal infection and the rate of wound healing were 21. 24％, 80. 50％, 16. 81％, 11. 50％, respectively. The delivery gestational week of the control group was(34. 0±1. 0) weeks, and the rate of postpartum hemorrhage, the rate of premature rupture of membranes, the rate of puerperal infection and the rate of wound healing were 10. 48％, 65. 70％, 7. 62％, 3. 81％, respectively. The delivery gestational week of the observation group was small. And the rate of premature rupture of membranes, wound healing failure rate, puerperal infection rate, postpartum hemorrhage rate in the observation group was significantly higher than that of the control group, and the difference was statistically significant(P＜0. 05). The mean neonatal weight in the observation group was(1710±355)g,and the asphyxia rate, early-onset sepsis rate, respiratory distress syndrome rate, pathological jaundice rate and neonatal mortality were 21. 24％, 33. 63％, 38. 05％, 19. 47％ and 9. 73％. The mean neonatal weight in the control group was(2270±450)g,and the asphyxia rate, early-onset sepsis rate, respiratory distress syndrome rate, pathological jaundice rate, neonatal mortality were 9. 52％, 18. 10％, 12. 38％, 8. 57％, 2. 86％. The average body weight of infants in the observation group was low. And the rates of early onset sepsis, asphyxia, respiratory distress syndrome, pathological jaundice and neonatal mortality were significantly increased. The difference was significant (P＜0. 05). Conclusion The placental pathology examination in all preterm patients should be done to avoid missed diagnosis of HCA, and to help early diagnosis and treatment of pregnant women with intrauterine infection and high-risk newborns and improve prognosis.