Abstract： The purpose of this study was to investigate the effect of cryptochrome 1 (CRY1) protein on the growth of bladder cancer xenograft tumor in nude mice and its effects on the proliferation and apoptosis of bladder cancer T24 cells. The study found that CRY1 over-expression inhibited the growth of the xenograft tumors, and the overexpressed CRY1 also inhibited the proliferation of T24 cells by promoting cell apoptosis. Therefore, targeting CRY1 protein may provide new ideation for treatment of bladder cancer.