Abstract: 　Objective　To explore the changes and significance of serum vitamin A levels in children with community acquired pneumonia. Methods　A total of 80 children with community-acquired pneumonia (pneumonia group) were selected from October 2015 to March 2016 and were divided into Mycoplasma pneumoniae (MP) infection group, bacteria infection group, MP and bacteria mixed infection group (mixed infection group) according to different pathogens. Thirty healthy children in the same period were selected as the control group. The serum vitamin A concentration was detected by ultra-highperformance liquid chromatography-tandem mass spectrometry. Results　The level of serum vitamin A was (0.567±0.163) μmol/L in pneumonia group, (0.578±0.162) μmol/L in MP infection group, (0.557±0.153) μmol/L in bacteria infection group and (0.554±0.186) μmol/L in mixed infection group, and all of them were lower than that in control group (0.759±0.160) μmol/L, and there were significant differences (P<0.05). There was no difference in serum vitamin A level among MP infection group, bacteria infection group and mixed infection group (P>0.05). There was a significant difference in the distribution of vitamin A deficiency between pneumonia group and control group ( P<0.001). The proportion of suspected subclinical vitamin A deficiency in control group was higher, while vitamin A deficiency and subclinical vitamin A deficiency in pneumonia group were higher. Conclusions　The serum vitamin A level decreased in children with community-acquired pneumonia, But there was no significant differences in serum vitamin A levels among the children with pneumonia caused by different pathogens.