Abstract: Objective To explore changes and significance of levels of serum C-reactive protein(CRP), procalcitonin(PCT), interleukin-6(IL-6) and brain natriuretic peptide(BNP) in patients with severe pulmonary infection. Methods A total of 467 patients with severe pulmonary infection who were admitted to Intensive Care Unit(ICU) of the Affiliated Hospital of Hangzhou Normal University from December 2015 to August 2019 were enrolled. According to age, patients were divided into 18-35 years group(172 cases), 36-60 years group(141 cases) and >60 years group(154 cases). According to survival within 30 d after admission in ICU, they were divided into survival group(349 cases) and death group(118 cases). Levels of serum CRP, PCT, IL-6 and BNP were measured. Pearson correlation analysis was applied to analyze correlation between age and CRP, PCT, IL-6, BNP. ROC curves were applied to analyze predictive value of CRP, PCT, IL-6 and BNP for prognosis of severe pulmonary infection patents at different age. Results The levels of serum CRP, PCT, IL-6 and BNP were significantly correlated with age(all P<0.05). The levels of CRP, PCT, IL-6 and BNP in the all survival group were significantly lower than those in the death group(all P<0.05). AUC of serum CRP, PCT, IL-6, BNP and their combination for predicting prognosis in 18-35 years group, 36-60 years group and >60 years group were(0.759, 0.729, 0.690, 0.798, 0.889),(0.813, 0.797, 0.713, 0.804, 0.927) and(0.644, 0.697, 0.696, 0.703, 0.847), respectively. Conclusion The levels of serum CRP, PCT, IL-6 and BNP are significantly correlated with age. The combined detection is of relatively higher predictive value for prognosis of patients with severe pulmonary infection at different age.