Objective To investigate the relationship between apolipoprotein CI and Wilms tumor stage.Methods A total of 50 children with wilms tumor admitted to the First Affiliated Hospital of Gannan Medical University from August 2010 to February 2022 were selected as the study group,and 20 healthy children in outpatient health examination were selected as the control group.Fasting blood samples were collected from the two groups in the morning,and fresh samples were taken from the study group.The serum apolipoprotein CI level was measured by ELISA,and the tumor tissue apolipoprotein CI level in the study group was measured by immunohistochemistry.The expression levels of apolipoprotein CI in serum and tissue of patients with different disease stages were compared between the study group and the control group,and the study group.The correlation between the expression levels of apolipoprotein CI in serum and tissue and the disease stage of Wilms tumor was analyzed.Results The serum apolipoprotein CI level in the study group was higher than that in the control group,and the difference was statistically significant (P＜0.05).The levels of apolipoprotein CI in serum and tumor tissues of children with different disease stages in the study group were significantly different (P＜0.05).The apolipoprotein CI levels in serum and tumor tissues of children with stage Ⅱwere higher than those of children with stage Ⅰ,those of children with stage Ⅲwere higher than those of children with stage Ⅱ,those of children with stage Ⅳwere higher than those of children with stage Ⅲ,and those of children with stage Ⅴwere higher than those of children with stage Ⅳ,the differences were statistically significant(P＜0.05).Correlation analysis showed that the levels of apolipoprotein CI in serum and tumor tissues were positively correlated with the stage of wilms tumor (P＜0.05).Conclusion Apolipoprotein CI is highly expressed in patients with Wilms tumor,and the detection of its level can evaluate the disease stage,provide a reference for clinical formulation or adjustment of intervention programs,and help ensure a good outcome of the disease.