Objective: To investigate the expression and clinical significance of serum vitamin A (VA),procalcitonin (PCT), tumor necrosis factor-α(TNF-α) and C-reactive protein (CRP) in premature infants with respiratory distress syndrome (RDS). Methods: 90 cases of preterm infants with RDS who were admitted to Qingdao Women's and Children's Hospital from February 2015 to May 2018 were selected as the observation group.According to RDS classification, the observation group was divided into mild group (48 cases) and moderate and severe group (42 cases). Another 35 non RDS preterm infants in our hospital in the same period were selected as control group. According to serum VA level, 125 cases of preterm infants were divided into VA deficiency group (n=72), subclinical VA deficiency group (n=36) and normal group (n=17). The serum VA, PCT, TNF-αand CRP levels were compared between the observation group and the control group, the mild group and the moderate and severe group. The incidence of RDS in preterm infants with different serum VA levels was compared. The correlation between serum VA and PCT, TNF- αand CRP levels in premature infants were analyzed. Results: The serum VA level of preterm infants in the observation group was significantly lower than that in the control group (P<0.05), while the serum PCT, TNF-αand CRP in the observation group were significantly higher than those in the control group (P< 0.05). There was no significant difference in serum VA level between moderate and severe group and mild group (P>0.05). Serum PCT, TNF-a and CRP in moderate and severe group were significantly higher than those in mild group (P<0.05). With the increase of serum VA level, the incidence of RDS decreased, and there was significant difference between groups (P<0.05). Pearson correlation analysis showed that there was no significant correlation between serum VA and PCT, TNF-αand CRP levels in preterm infants in the observation group (P>0.05). Conclusion: There are obvious abnormalities in serum VA, PCT, TNF-αand CRP levels in preterm infants with RDS, but there are no significant correlations in them.Patients with relatively low serum VA are more likely to develop RDS, clinical intervention can reduce the risk of RDS through timely intervention of VA level. [ABSTRACT FROM AUTHOR]