Objective: This study aims to explore the influencing factors of posttraumatic stress disorder (PTSD) and its correlation with psychological resilience in pregnant women who are threatened with preterm labor. Methods: A total of 200 pregnant women with possible preterm labor who were treated in our hospital were included in this case-control study for retrospective analysis. The Connor-Davidson Resilience Scale (CD-RISC), Social Support Rating Scale (SSRS) and Pregnancy Pressure Scale (PPS) questionnaires were used to assess stress before delivery, and the baseline clinical data and peripartum data were collected at the same time. The PTSD checklist-civilian version (PCL-C) scale was used for evaluation and the incidence of PTSD in pregnant women was evaluated by followup at 6 weeks after delivery. According to the score of PCL-C scale, pregnant women were divided into the PTSD positive group and PTSD negative group. Univariate and multivariate logistics regression were used to analyze the influencing factors of PTSD in pregnant women who were threatened with preterm labor, and Pearson correlation coefficient was used to evaluate the correlation between PTSD and psychological resilience in pregnant women with possible preterm labor. Results: Among the 200 pregnant women, 43 had a PCL-C score = 38, and the PTSD positive rate was 21.50%. The scores of CD-RISC and SSRS scale of PTSD positive group were significantly lower than those of PTSD negative group (P<0.05), while the score of PPS scale was significantly higher than that of PTSD negative group (P<0.05). Multivariate logistics regression analysis showed that the sleep status (OR=3.156), the pregnancy stress (OR=3.274) and the history of anxiety and depression (OR=5.174) were independent risk factors for PTSD in pregnant women with possible preterm labor, the while CD-RISC score (OR=0.259), social support (OR=0.468) and fetal weight (OR=0.568) were protective factors for PTSD in pregnant women with indicated preterm labor. Pearson correlation analysis showed that the total score of PCL-C in pregnant women with indicated preterm labor was negatively correlated with the total score of CD-RISC (0.428), toughness (0.475), strength (0.331) and optimism (0.465). Conclusion: Maternal sleep status, pregnancy stress, history of anxiety and depression are independent risk factors of PTSD in pregnant women with possible preterm labor, while the level of psychological resilience of pregnant women is the protective factor of PTSD in pregnant women with possible preterm labor. Active psychological intervention in pregnant women with predicted preterm labor is helpful to reduce the risk of PTSD in pregnant women.