This study aims to explore the clinical significance of C-reactive protein, leukocyte and immunoglobulin in the diagnosis and treatment of infantile pneumonia at acute stage. From January to December 2018, a total of 124 children with pneumonia and healthy children admitted to our hospital were selected as study objects. Among them, 62 children diagnosed with bacterial pneumonia were categorized as the study group, and 62 healthy children who came for physical examination were classified as the control group. The levels of C-reactive protein (CRP), white blood cell (WBC) and immunoglobulin (IgA, IgM and IgG) were observed and compared in the two groups. In this study, higher levels of CRP, IgM, IgG and WBC, along with lower level of IgA were observed in the study group as compared with that in the control group. In the study group, the levels of CRP, IgM, IgG and WBC were lower, but the IgA level was higher in children with mild pneumonia than those with severe pneumonia. After treatment, the levels of CRP, IgM, IgG and WBC were decreased but IgA level was increased after treatment compared with before treatment. In particular, the levels of CRP, WBC, IgA, IgM and IgG in the study group after treatment were restored to comparable levels compared with the control group. Therefore, C-reactive protein, leukocyte and immunoglobulin can be used to determine the diagnosis, condition and outcome of children with pneumonia in the acute stage. This study can provide guidance for clinical diagnosis and treatment of infantile pneumonia based