Background: Postpartum depression causes harm to both mothers and infants. The purpose of this study was to find out several potential risk factors, and to identify the intrinsic interrelationships between factors and postpartum depression by constructing a path model. The results of this study may help to control the increasing incidence of maternal postpartum depression. Methods: The study was based on a sample of mothers from a cross-sectional study which was set up at 4 weeks after a mother had childbirth and was conducted in three streets at Kaifu District of Changsha in Hunan province from January to December 2015. Questionnaires were distributed to subjects who responded to questions concerning factors related to pregnancy, delivery and infants within 4 weeks after childbirth. The Edinburgh Postnatal Depression Scale (EPDS) was used to measure postpartum depression. Chi-square test was used to detect significant differences between non-postpartum depression group and postpartum depression group. A path model was constructed to explore the interrelationships between variables, and to verify the relationships between variables and postpartum depression. Results: The proportion of maternal postpartum depression was 6.7%. Univariate analysis showed that there were significant differences between non-postpartum depression group and postpartum depression group (all P-values <0.05) on the part of maternal age, parity, frequent exposure to mobile phone during pregnancy, gestational hypertensive disorders, fetus number, premature delivery, birth weight, initiation of breastfeeding, mode of feeding, infant illness within 4 weeks after delivery and infant weight at 4 weeks. Path analysis results showed that the final model could be fitted well with sample data (P = 0.687, CMIN/DF = 0.824, NFI = 0.992, RFI = 0.982, IFI = 1.002, TLI = 1.004, CFI = 1.000 and RMSEA < 0.001). Frequent exposure to mobile phone during pregnancy, maternal age and gestational hypertensive disorders had both direct and indirect effects on postpartum depression. Mode of feeding and infant weight at 4 weeks, which was the most total effect on postpartum depression, had only a direct impact on postpartum depression. Fetus number, premature delivery, initiation of breastfeeding and birth weight had only an indirect influence on postpartum depression. Conclusion: The findings of this study suggest that constructing a path analysis model could identify potential factors and explore the potential interrelations between factors and postpartum depression. It is an effective way to prevent maternal postpartum depression by taking appropriate intervention measures and carrying out health education for pregnant women.