Abstract: Lactobacillus is a probiotic that is important for human health and microecological balance. It is widely distributed in the gastrointestinal tract and reproductive tract of the human body. In recent years, it has been found that Lactobacillus has a positive effect in the prevention and treatment of cancer. In this paper, the inhibitory effects of Lactobacillus on various tumors, and the anti-tumor mechanism of Lactobacillus by inhibiting carcinogen production, activating humoral immunity, activating cellular immunity and promoting tumor cell apoptosis were reviewed, providing a theoretical basis for further research on anti-tumor of Lactobacillus. With further research of anti-tumor activity of Lactobacillus, it is of great significance to the exploitation of new anti-tumor drugs and the development of biological technology to prevent tumors.