Abstract: Objective　To explore the relationship between the levels of IL-17 and IL-35 in peripheral blood and progression of bronchial asthma in children and the significance of their detection. Method　A total of 65 hospitalized children with acute exacerbation of bronchial asthma from May 2016 to May 2017 were selected as the research object. According to the severity of the disease, those children were divided into intermittent asthma, mild persistent asthma, moderate persistent asthma and severe persistent asthma groups. At the same time, 20 healthy children were taken as the control group. The serum levels of IL-17 and IL-35 were detected by enzyme-linked immunosorbent assay (ELISA), and the statistical analysis was performed. Results　The IL-17 level in asthma group (49.9±12.5 pg/mL) was higher than that in control group (34.7±7.2 pg/mL), and there was significant difference (P<0.05). The level of IL-17 increased with the severity of asthma, and was negatively correlated with lung function indexes of FEV1, FVC, and FEV1/FVC (P<0.05). The IL-35 level in asthma group (171.2±18.8 pg/mL) was lower than that of control group (264.2±33.7 pg/mL), and there was significant difference (P<0.05). The level of IL-35 decreased with the increase of the severity of asthma, and was positively correlated with the index of lung function (P<0.05). When IL-17>42.6 pg/mL and IL-35<205.8 pg/mL are chosen as cut-off values respectively, both of them can achieve high diagnostic values in sensitivity, specificity, accuracy, positive predictive value, negative predictive value and area under the curve (AUC). Combination of both can further improve the diagnostic value. Conclusion　The levels of L-17 and IL-35 in serum of children with asthma can be used as a reference for assessing the severity of disease, and may be a good biomarker for the diagnosis of childhood asthma.