Objective @# To the effects and potential mechanisms of ST3GAL5 on biological behaviors of Bladder Urothelial Carcinoma(BLCA) . @*Methods @# Differentially expressed genes related to bladder cancer were identified using microarray analysis . Suitable bladder cancer cell lines were then screened . In vitro experimental measurements , including CCK8 , EdU , colony formation assays , transwell migration , flow cytometry apoptosis experiments , scratch assay , were used to evaluate the effects of ST3GAL5 on biological behaviors of BLCA . ST3GAL5 gene Kyoto Encyclopedia of Genes and Genomes ( KEGG) , gene set enrichment analysis ( GSEA) were analyzed using The Cancer Genome Atlas (TCGA) database . Finally , Western blot technology was used to verify the classical proliferation and metastasis related pathway factors . @*Results @# The combination of bioinformatics analyses and experimental measurements demonstrate that ST3GAL5 expression is aberrantly down⁃regulated in human cell lines of BLCA . Through Cancer Cell Line Encyclopedia (CCLE) database , HT⁃1376 cell lines were successfully screened for vitro test . Upregulation of ST3GAL5 was found to suppress the malignant biological behaviour of bladder cancer. GSEA enrichment analyses exhibited that ST3GAL5 and its co⁃expressed genes inhibited cell proliferation , invasion and metastasis of bladder urothelial carcinoma by activation of the PPAR pathway and inhibition of the PI3K/AKT pathway . The results of Western blot experiments verified that the key proteins of the PPAR signaling pathway showed a significant increase and the key proteins of the PI3K/AKT signaling pathway showed a significant decrease ( P <0. 05) after ST3GAL5 overexpression in bladder cancer. @*Conclusion @#ST3GAL5 gene might act as an oncogenic suppressor gene in bladder cancer , possibly inhibit the proliferation , invasion and metastasis of bladder cancer cells by activating the PPAR signaling pathway and inhibiting related molecules in the PI3K/AKT signaling pathway .