Abstract: Background　Atopobium parvulum may be involved in the occurrence and development of colorectal cancer (CRC), and relevant research on this bacterium remains scarce at present. Objective　To investigate the effect of Atopobium parvulum on the apoptosis of colorectal cancer cells and its underlying molecular mechanism.Methods　Human normal colonic epithelial cells (NCM460) and colorectal cancer cell lines (SW480 and MC38) were incubated for 24 hours with the supernatants of Atopobium parvulum, Fusobacterium nucleatum, Escherichia coli, and pure bacterial medium, respectively. Western blot (WB) and flow cytometry (FC) were used to detect phenotypic changes such as cell apoptosis, and the CCK-8 assay was applied to determine the effect of Atopobium parvulum on cell proliferation. Results　After incubating human normal colonic epithelial cells and colorectal cancer cells with 15% Atopobium parvulum supernatant for 24 hours, the level of the apoptotic marker cleaved caspase 3 was decreased, and the bcl2/bax ratio was increased. Meanwhile, flow cytometry results showed a reduction in the number of apoptotic colorectal cancer cells; the CCK-8 assay revealed an increase in the cell viability level of colorectal cancer cells. Incubation of colorectal cancer cells with 15% Atopobium parvulum supernatant for 24 hours activated the PI3K/AKT signaling pathway, and the PI3K/AKT signaling pathway inhibitor PI3K/AKT-IN-1 reversed the inhibitory effect of Atopobium parvulum on colorectal cancer cell apoptosis. Conclusion　Atopobium parvulum inhibits the apoptosis and promotes the cell viability ofcolorectal cancer cells by activating the PI3K/AKT signaling pathway, thereby playing a role in facilitating the occurrence and development of colorectal cancer.