Objective:To investigate the risk factors of respiratory distress syndrome (RDS) complicated by pulmonary hemorrhage (PH) in premature infants.Methods:A total of 102 infant patients with RDS whose gestational age was < 37 weeks received treatment in the Department of Neonatology, Kunming Children's Hospital (Children's Hospital Affiliated to Kunming Medical University) from January 2015 to July 2021 and were included in this study. According to the diagnostic criteria of PH, these infant patients were divided into a PH group and a non-PH group. The clinical data of the two groups were compared using a t-test, non-parametric test, or χ2 test. The risk factors of PH were analyzed. The independent risk factors of RDS complicated by PH in premature infants were determined using multivariate logistic regression analysis. Results:A total of 102 premature infants with RDS were collected, including 51 in the PH group and 51 in the non-PH group. The gestational ages at birth were (32.3 ± 3.0) weeks and (31.6 ± 3.0) weeks in the PH and non-PH groups, respectively. There were 36 males (70.6%) and 33 males (64.7%) in the PH and non-PH groups, respectively. There were no significant differences in proportion of males and gestational ages at birth between the two groups (both P > 0.05). The incidence of gestational age < 32 weeks [52.9% (27/51) vs. 31.3% (16/51)], PH and RDS complicated by patent ductus arteriosus [90.5% (38/42) vs. 70.0% (35/50)], and RDS grade 3-4 [80.4% (41/51) vs. 23.5% (12/51)] in the PH group were significantly higher than those in the non-PH group ( χ2 = 5.29, 4.66, 33.03, all P < 0.05). Multivariate logistic regression analysis showed that RDS grade 3-4 was an independent risk factor of RDS complicated by PH ( OR = 9.83, 95% CI: 3.545-27.265, P < 0.05). The proportion of infants with mechanical ventilation time ≥ 7 days in the PH group was significantly higher than that in the non-PH group [56.9% (29/51) vs. 31.4% (16/51), χ2 = 6.72, P < 0.05]. Conclusion:Gestational age < 32 weeks, PH and RDS complicated by patent ductus arteriosus, and RDS grade 3-4 are the risk factors of PH in premature infants with RDS. RDS grade 3-4 is an independent risk factor.