Abstract： Objective To investigate the effect of human immunoglobulin combined with acetylcysteine on the clinical symptoms and oxidative stress level of neonatal pneumonia.Methods A total of 86 cases of neonatal pneumonia in The First People's Hospital of Shangqiu(January 2021-October 2023)were retrospectively selected and divided into experimental group and control group,43 cases in each group according to different treatment methods.Both groups were given conventional treatment,on the basis of which the control group was given acetylcysteine treatment,and the experimental group was given human immunoglobulin combined with acetylcysteine treatment.The clinical efficacy,symptom improvement,oxidative stress[advanced oxidation prorein products(AOPP),glutathione peroxidase(GSH-Px),superoxide dismutase(SOD)],immune function(CD3+,CD8+,CD4+/CD8+ratio)and adverse reactions were compared between the two groups.Results The total effective rate of experimental group was 93.02%higher than that of 76.74%control group(P<0.05).Compared with the control group,the disappearance time of pulmonary moist rales,cough,shortness of breath and absorption time of thoracic inflammation in experimental groups were significantly shortened(P<0.05).After 7 days of treatment,the levels of SOD and GSH-Px in serum of 2 groups were higher than before treatment,and the levels of AOPP were lower than before treatment,and the improvement of experimental group was better than that of control group(P<0.05).Compared with before treatment,the ratio of CD3+and CD4+/CD8+in both groups increased and CD8+decreased after 7 days of treatment,and the improvement in experimental group was more significant(P<0.05).There was no significant difference in the incidence of adverse reactions between the two groups(P>0.05).Conclusion Human immunoglobulin combined with acetylcysteine is effective in the treatment of neonatal pneumonia,which is helpful to improve immune function,reduce oxidative stress,shorten rehabilitation process,and has high safety.