Objective : To analyze the expression and clinical significance of circ⁃RACGAP1 in bladder cancer tissues , and to explore the influence and mechanism of circ⁃RACGAP1 on the malignant biological behavior of bladder cancer cells. Methods : The expression of circ⁃RACGAP1 in bladder cancer tissues was explored through the TCGA database , and the relationship between the expression of circ⁃RACGAP1 and the clinicopathological features of bladder cancer patients was analyzed. The expression of circ⁃RACGAP1 in cell lines 5637 , T24 , J82 , RT⁃4 and UM⁃UC⁃3 was analyzed by quantitative real⁃time PCR (qPCR) . The circ⁃RACGAP1 knockdown plasmid was transfected into T24 cells by lipofection technology. Colony formation assay , scratch assay and Transwell assay were used to analyze the effects of knocking down circ⁃RACGAP1 on the proliferation , migration and invasion of T24 cells , respectively. The targeted binding between circ⁃RACGAP1 and miR⁃4324 was verified using deepBase , Circbank , CircInteractome , circRNABase databases and a fluorescent reporter system. The effect of knocking down circ⁃RACGAP1 on the expression of miR⁃4324 in T24 cells was detected by qPCR. Western blot was used to detect the effect of knocking down circ⁃RACGAP1 on the expression of recombinant rac⁃GTPase activating protein 1 (RACGAP1) protein and phosphatidylinositol⁃3 ⁃kinase/protein kinase B (PI3K/AKT) signaling pathway proteins in T24 cells. Results circ⁃RACGAP1 was highly expressed in bladder cancer tissues (P < 0. 01) , and its expression increased with the clinical stage of the patients ( P < 0. 01) . The expression of circ⁃RACGAP1 in bladder cancer cell lines was significantly higher than that in normal human bladder epithelial cells ( all P < 0. 01) . Compared with the control group , the proliferation , migration and invasion abilities of T24 cells in the sh⁃circ⁃RAC⁃GAP1 group significantly decreased (all P < 0. 01) . circ⁃RACGAP1 could target and inhibit the expression of miR⁃4324 (P < 0. 01) . Compared with the control group , the expression level of RACGAP1 protein in T24 cells in the sh⁃circ⁃RACGAP1 group decreased (P < 0. 01) , and the expression levels of PI3K/AKT signaling pathway proteins phosphatidylinositol⁃3 ⁃kinase (p⁃PI3K) , phosphorylated protein kinase B (p⁃AKT) , nuclear factor kappa B (NF-κB) decreased (all P < 0. 01) . Conclusion circ⁃RACGAP1 is highly expressed in bladder cancer tissues and cell GAP1 plays a role by inhibiting the expression of miR⁃4324 and activating the PI3K/AKT signaling pathway.