Abstract: Objective To investigate the effects of budesonide aerosol inhalation on immune function and adverse reactions in children with asthma. Methods A simple random sampling method was used to select 100 asthmatic children, and they were divided into two groups according to lottery method. The control group(n=50)received routine treatment, and the study group(n=50)received budesonide atomization inhalation. The levels of inflammation as well as lung function indexes, immune function indexes and adverse reactions were compared between the two groups. Results After treatment, interleukin-4(IL-4)and interleukin-6(IL-6)in the study group were lower than those in the control group, and interferon γ(IFN-γ)was significantly higher that in the control group(P<0.05); forced vital capacity(FVC), forced expiratory volume in 1 second(FEV₁), 25% maximum expiratory capacity(MEF₂₅)in the study group were higher than those in the control group(P<0.05); the levels of CD4⁺ and CD4⁺/CD8⁺ in the study group were higher, and level of CD8⁺ was lower than that in the control group(P<0.05); the incidence of adverse reactions was 4.00% in the study group and 8.00% in the control group, but there was no significant difference(P>0.05). Conclusion Budesonide aerosol inhalation in the treatment of children with asthma can reduce inflammation reaction, improve lung function and immune function, and reduce adverse reactions.