Abstract: OBJECTIVE To explore the inhibitory effect of delphinidin on proliferation inhibition and apoptosis induction of human bladder cancer cell line T24 and its related molecular mechanism. METHODS T24 cells were cultured in vitro, and the killing effect of delphinidin on human bladder cancer T24 cells was detected by CCK-8 assay. Apoptosis and reactive oxygen species levels were detected by flow cytometry. Apoptosis correlation protein and signaling pathway-related proteins expression were detected by Western blotting. RESULTS Delphinidin could effectively inhibit the proliferation of human bladder cancer T24 cells with an IC₅₀ of (42.37±2.82)μmol·L^-1; delphinidin could induce apoptosis of T24 cells through mitochondria- dependent pathway, making Cyt-c, cleaved-Caspase-3, PARP and Bax protein expression increased, Bcl-2 expression decreased; delphinidin could reduce reactive oxygen species levels in T24 cells and activate JNK/STAT3 signaling pathway. CONCLUSION Delphinidin has a good killing effect on human bladder cancer T24 cells, and can induce mitochondria- dependent apoptosis in T24 cells by decreasing the level of reactive oxygen species in T24 cells and regulating JNK/STAT3 signaling pathway.