Abstract: The gut microbiota constitutes a vital component of the complex micro-ecosystem within the human body. It interacts with the host and influences diverse pathophysiological processes, including inflammation, immunity, and tumorigenesis. Advances in metagenomics technology have greatly promoted research into the gut microbiota, revolutionizing our understanding of its associations with human health and disease. Substantial evidence indicates that gut microbiota dysbiosis is closely linked to the pathogenesis and progression of gastrointestinal tract tumors. Dysbiosis can directly or indirectly promote the development of these tumors by modulating host immune responses, fostering chronic inflammation, and impairing intestinal barrier function. This article reviews the relationship between gut microbiota dysbiosis and gastrointestinal tract tumors, as well as the underlying mechanisms influencing their initiation and progression, aiming to provide a theoretical basis for future research on precision diagnosis and treatment for oncology.