Abstract: Objective 　To investigate the anticancer effect s of Janus Kinase-selective inhibitor AG490 in human bladder cancer. Methods 　The bladder cancer cell line BIU-87 was treated with AG490 in different doses. The cell vitality and proliferation were detected by Trypan Blue staining rejection, cell counting and MTT assay. Drug sensitivity of bladder cancer stem cells to A G490 was detected by clone formation counting assay. Fluorescence dyestuff Hoechst33258 and PI double-staining assay was used to investigate the cell apoptosis characteristics. Flow cytometry was applied to analyze the cell cycle and apoptosis. The expressions of phosphorylation-specific JAK2 (p-JAK2 ), STAT3, phosphorylation-specific STAT3 (p-STAT3), Cyclin D1 and bcl-xL were measured by western blot . Results 　AG490 could remarkably inhibit the proliferation of bladder cancer cells and the formation of the tumor stem cell clones, block the cell cycle, facilitate the apoptosis of bladder cancer cells, and result in less expression of p-JAK2, STAT3, p-STAT3, Cyclin D1 and bcl-xL. Conclusion 　AG490 showed st rong abilities of inhibiting the proliferation of bladder cancer cells and inducing their apoptosis through blocking the STAT3 signaling pathway.