Abstract: OBJECTIVE To explore the changes of interleukin (IL)-4 and interferon--γ(IFN-γ)in alveolar lavage fluid of the influenza A (H1N1) children complicated with Mycoplasma pneumoniae infections and observe the values in prediction of therapeutic effects. METHODS A total of 118 H1N1 children complicated with M. pneumoniae infection who were treated in Lu'an People's Hospital from Aug. 2022 to Mar. 2025 were assigned as the study group, meanwhile, 50 children with simple M. pneumoniae infection were chosen as the control group. The levels of alveolar lavage fluid IL-4, IFN-γ and the ratio of IFN-γ to IL-4 were detected and compared between the wo groups of children. The 118 influenza A H1N1 infection children complicated with mycoplasma pneumoniae infection were divided into the ineffective group with 32 cases and the effective group with 86 cases according to the therapeutic effects. The predictive efficiencies were evaluated by means of receiver operating characteristic (ROC) curves. RESULTS The alveolar lavage fluid IL-4, IFN-γ, and the ratio of IFN-γ to IL-4 were respectively (58.32±4.68)pg/ml, (60.29±11.28)pg/ml and (0.97±0.31) in the control group, (99.64±15.40)pg/ml, (142.04±26.45)pg/ml, and(0.70±0.26) in the study group; the levels of IL-4 and IFN-γ of the study group were higher than those of the control group, while the ratio of IFN-γ to IL-4 of the study group was lower than that of the control group (P＜0.05). 32 of 118 children who received symptomatic treatment progressed to RMPP due to ineffective treatment. The duration of fever of the ineffective group was longer than that of the effective group, the levels of alveolar lavage fluid IL-4 and IFN-γ of the ineffective group were higher than those of the effective group, and the ratio of IFN-γ to IL-4 of the ineffective group was lower than that of the effective group( all P＜0.05). ROC curve analysis showed that the AUCs of IL-4, IFN-γ and the ratio of IFN-γ to IL-4 were respectively 0.804, 0.817 and 0.931 in prediction of therapeutic effects, and the predictive efficiency of the ratio of IFN-γ to IL-4 was relatively high. CONCLUSION The rise of alveolar lavage fluid IL-4 and IFN-γ is closely associated with the M. pneumoniae infection in the H1N1 children and is the risk factor for the failed treatment. The ratio of IFN-γto IL-4 is the protective factor and has high predictive value.