Abstract: OBJECTIVE To analyze the pathogen distribution and explore its effect on pulmonary function in infected severe pneumonia children, so as to provide reference for clinical diagnose and treatment. METHODS A total of 140 cases of infected severe pneumonia patients in our hospital from Dec. 2010 to Nov. 2014 were enrolled in this investigation as infected group, another 140 cases of healthy children had health check in this hospital as control group, and 140 cases of uninfected severe pneumonia children as uninfected group. The data from these three groups were under comparison using SPSS 19.0 to analyze. RESULTS A total of 140 stains of pathogens were identified from the 140 patients. The pathogens contained 83 (59.29%) gram-negative strains as the main part. The FEV1, FVC and FEV1/FVC as well as FEV1/predicted value and fibrinogen were decreased significantly in infected children. The results also showed that the level of serum surfactant protein and transcription factor activated protein was decreased dramatically in infected children, which had significant different comparing to control group and uninfected group (P<0.05). CONCLUSION Severe pneumonia children are mainly suffered from gram-negative bacteria and the pulmonary function and level of serum surfactant protein and transcription factor are decreased after infection.