Abstract: Objective To investigate the effect of bronchoscopic alveolar lavage on inflammatory response and blood gas index in children with severe pneumonia. Methods A total of 94 children with severe pneumonia in our hospital were randomly divided into control group and observation group, with 47 cases in each group. The control group was given routine symptomatic treatment, such as anti-infection, atomized inhalation therapy, and back-patting sputum expectoration, antispasmodic, antipyretic treatments and correction of water electrolyte disorder. The observation group was given bronchoscopic alveolar lavage on the basis of the control group, the treatment was lasted for 7 days. The changes of serum C reactive protein(CRP), procalcitonin(PCT), tumor necrosis factor-α(TNF-α), arterial oxygen partial pressure ［p(O₂)］, arterial oxygen saturation(SaO₂), arterial carbon dioxide partial pressure［p(CO₂)］, acute physiology and chronic health status Ⅱ(APACHE-Ⅱ)scores before and after treatment were observed,and the clinical effects of the two groups were evaluated. Results After treatment, the levels of serum CRP, PCT and TNF-α in the two groups were significantly lower than those before treatment(P< 0.05), and were significantly lower in the observation group than those in the control group(P< 0.05). After treatment, p(O₂)and SaO₂ in the two groups were significantly higher, and p(CO₂)was significantly lower than treatment before(P<0.05), and the observation group changed more significantly compared with the control group(P<0.05). After treatment, APACHEⅡscore in the observation group was significantly lower(P<0.05), and total effective rate was significantly higher than that in the control group - (95.74% vs. 80.85%, P<0.05). Conclusion Bronchoscopic alveolar lavage can effectively reduce the inflammatory reactions and improve the blood gas index level, and improve the clinical effects in children with severe pneumonia.