Objective To analyze the correlation between serum soluble Klotho protein(sKL)and tendino-C(TN-C)and the severity of disease and oxidative stress in children with immunoglobulin A(IgA)nephropa-thy.Methods A total of 85 children with IgA nephropathy admitted to the hospital from July 2019 to August 2022 were selected as IgA nephropathy group,and 85 healthy patients who underwent physical examination in the hospital during the same period were selected as healthy group.Serum sKL and TN-C levels were com-pared between the two groups.Receiver operating characteristic(ROC)curve was drawn to analyze the value of serum sKL,TN-C and their combination in predicting the occurrence of IgA nephropathy.IgA nephropathy group was divided into mild group(28 cases),moderate group(39 cases)and severe group(18 cases)accord-ing to 24 h urinary protein quantity.Serum sKL,TN-C levels and oxidative stress indexes[malondialdehyde(MDA),superoxide dismutase(SOD)and advanced oxidation protein product(AOPP)]of the three groups were compared.The correlation between serum sKL and TN-C levels and oxidative stress indexes was ana-lyzed by Spearman correlation,and the correlation between serum sKL and TN-C levels and the severity of IgA nephropathy in children was examined by Kendall's Tau-b.Results The serum sKL level in IgA ne-phropathy group was lower than that in healthy group,and the serum TN-C level was higher than that in healthy group,the difference was statistically significant(P＜0.05).ROC curve showed that the area under the curve and 95％CI of serum sKL,TNC and their combination predicted the occurrence of IgA nephropathy were 0.726(95％CI:0.648-0.803),0.853(95％CI:0.796-0.909)and 0.891(95％CI:0.845-0.937).The level of serum sKL in severe group was lower than that in moderate and mild groups,while the level of serum TN-C was higher than that in moderate and mild groups,and the difference was statistically significant(P＜0.05).The serum SOD level of severe group was lower than that of moderate group and mild group,and the serum AOPP and MDA levels were higher than those of moderate group and mild group,the difference was statistically significant(P＜0.05).Spearman correlation showed that sKL level was positively correlated with SOD(r＞0,P＜0.05),and negatively correlated with AOPP and MDA(r＜0,P＜0.05).TN-C level was negatively correlated with SOD(r＜0,P＜0.05),and positively correlated with AOPP and MDA(r＞0,P＜0.05).Conclusion The levels of serum sKL and TN-C in children with IgA nephropathy are related to the severity of disease and oxidative stress,and the combination of SKL and TN-C can effectively predict the occurrence of IgA nephropathy.