Tumor immunotherapy is a therapeutic method that uses the immune system to restore the body′s normal anti⁃tumor immune response, to control and remove the tumor. Intestinal microbiota can maintain the homeostasis and the health of the body by interacting with the host and play a crucial role in the process of human physiological activities. More and more studies have found that intestinal microbiota affects the occurrence and development of tumors. And the disorders of intestinal microbiota and potential mechanisms in patients with tumors have also been gradually analyzed. At the same time, the intestinal flora of patients also plays a decisive role, it has been found that the regulation of immune response by intestinal microbiota may directly affect the therapeutic effect of cancer in the process of tumor immunotherapy. Artificial intervention to change intestinal microbiota can be used as a new strategy to improve the effect of tumor immunotherapy and achieve accurate and personalized treatment of cancer in combination with conventional immunotherapy. The intervention measures include antibiotics, probiotics, and so on. Among them, probiotics, a kind of safe and effective microecological agents, have great potential in tumor immunotherapy used to interfere with intestinal microbiota, but more clinical data and mechanisms are still needed. This paper introduces the relationship between intestinal microbiota with tumor and the research progress of probiotics in tumor immunotherapy, which provides theoretical support for the application of probiotics and the mechanism of probiotics affecting host health.