Background: Parents’ postnatal sense of security is very important to the postnatal experience, and has a positive effect on parental role adaptation, the mental health of parents, marital relationship, and the parent-child relationship. This cross-sectional study was conducted to describe the status quo of Chinese parents’ postnatal sense of security within one week after delivery, and identify their related factors. Methods: Participants were recruited through the convenience samples methods in three grade-A tertiary hospitals in China. The Parents’ Postnatal Sense of Security (PPSS), the Readiness for Hospital Discharge Study-New Mother Form (RHDS-NMF) (for mothers), Edinburgh Postnatal Depression Scale (EPDS) and Zung’s Self-Rating Anxiety (SAS) were administered between October 2020 and January 2021. Descriptive analysis was used to understand the status quo of parents' postnatal sense of security, one-way ANOVA or independent sample t-tests and enter-method multiple linear regression analysis were used to identify the influence factors, Pearson correlation were used to examine the correlation between the total scores of parents’ postnatal sense of security. Results: A total of 204 pairs of parents were recruited into this study. The mean total score on the mothers’ version of PPSS was 59.67 (SD = 7.95) and fathers’ version of PPSS was 42.91(SD = 5.18), Multiple linear regression analysis showed that factors of mothers’ postnatal sense of security included the relations with husband's parents, length of stay in hospital after delivery, knowledge from health care workers and the Internet, depression, discharge readiness, fathers’ postnatal sense of security, explained 73.3% of the variance (R2 = 0.733, F = 17.125, p < 0.001). Fathers’ postnatal sense of security was significantly associated with parenting confidence, knowledge from health care workers, depression, anxiety, and mothers’ postnatal sense of security, explained 62.7% of the variance (R2 = 0.627, F = 21.092, p < 0.001). Conclusion: The level of parents’ postnatal sense of security was upper-middle among Chinese parents. The study identified factors associated with parents’ postnatal sense of security that could be targeted for intervention to facilitate parents’ postnatal sense of security.