The intestinal flora, a crucial system of microorganisms in the human body, is crucial to the immune system, metabolism, and inflammatory response of the body. The intestinal flora is one of them, and as a crucial element of the gastrointestinal microecology, it has a significant impact on the development and spread of gastrointestinal cancer as well as its management. The study of intestinal flora has become more in-depth recently as a result of the quick advancement of high-throughput sequencing technology, and the role of intestinal flora in the development and prognosis of gastrointestinal cancer is becoming increasingly obvious. In this article, the key topics covered include the links between Helicobacter pylori and gastric cancer, as well as the relationship between Fusobacterium and colon cancer, and discusses the mechanism by which intestinal microbes affect the treatment of gastrointestinal cancer. The link between gut microbiota and gastrointestinal cancer was further clarified, and the regulation of gut microbiota was proposed as a new management method for the clinical gastrointestinal cancer treatment.