Objective: To analyze the serum vitamin D level in infants with pneumonia. Methods: 424 cases of pneumonia infants in our hospital form 2015.1 to 2015.12 were taken as case group and divided into 4 groups according to months of age; 644 healthy infants were taken as control group in our hospital at the same term. Euzymelinked immunosorbent assay was used to detect the serum 25-(OH)D level of all infants. Results: The serum 25-(OH)D level of pneumonia infants was obviously lower than healthy infants (P<0.01); And, the serum 25-(OH)D level of pneumonia infants of 1-3 months, 4-6 months and 9-12 months were all obviously lower than the same age healthy infants (P<0.01, P<0.05). The incidence of vitamin D deficiency in pneumonia infants was 52.36% (222/424), which was significantly higher than healthy infants (30.59%, P<0.01). Conclusions: Infants with vitamin D deficiency maybe more likely to suffer pneumonia; Pneumonia infants and healthy infants all should pay attention to vitamin D supplementation.