Objective To conduct comparative proteomics study between the stenotic and the normal ureteral tissues adjacent to the stenotic ureter in children with ureteropelvic junction ( UPJ) stenosis, and explore the etiology and pathogenesis of congenital UPJ stenosis. Methods 30 children with congenital UPJ stenosis underwent Anderson-Hynes operation. The ureteral tissue of the narrow segment (group A) and the normal ureteral tissue adjacent to the distal end of the stenosis ( group B) were taken immediately after the operation. A relative quantitative method of high-throughput proteomics based on tandem mass tag ( TMT) was used to screen the differentially expressed proteins in these two groups. And then the targeted proteomics quantitative verification of the screened differential proteins was carried out by parallel reaction monitoring ( PRM) . Gene Ontology (GO) functional annotation, Kyoto Encyclopedia of genes and genomics (KEGG) pathway were enriched and analyzed by bioinformatics method, and protein-protein interaction ( PPI) network was analyzed. Results A total of 6093 proteins were identified in the two groups of specimens, including 160 differential proteins, of which 65 were up-regulated and 95 were down-regulated. Among the 9 target proteins subjected to PRM relative quantitative analysis, the ratio of protein content of 7 proteins including carbonic anhydrase 1 in group A and group B was less than 1 in the quantitative results of PRM and TMT; Glypican The ratio of protein content of -6 and RNA-binding proteins with multiple splicing in group A to group B was greater than 1 in the quantitative results of PRM and TMT. GO functional enrichment analysis found that the GO functional enrichment of differentially expressed proteins in the two groups in biological processes such as humoral immune response, anti-microbial humoral response, response to fungi, defense response to fungi, and defense response to bacteria were significantly higher. High level of significance( P < 0. 05) . The results of KEGG pathway enrichment analysis showed that the enrichment of 20 signaling pathways including nitrogen metabolism and PPAR signaling pathway had a high significant level ( P < 0. 05) . In the PPI network, the most connected proteins were: neutrophil elastase (connectivity of 9) and cathepsin antimicrobial peptide (connectivity of 8) . Conclusion The results of comparative proteomics suggest that the pathogenesis of congenital UPJ stenosis is related to microbial infection, which provides a reference for further study on the etiology and pathogenesis of this disease. [ABSTRACT FROM AUTHOR]