Colorectal cancer is one of the most common cancers, ranking the third in the incidence of cancer in China. Intestinal microenvironment affects tumor proliferation, survival, metastasis, and tumorigenesis, especially metabolites in the microenvironment can stimulate inflammatory cells to induce chronic inflammatory responses. The intestinal flora affects the mechanism of the body and regulates the physiological function of the colon, rectum and even the whole digestive system, which is closely related to colorectal cancer. At present, sequencing technology and microbiota⁃host interaction are the main methods to study the association between gut microbiota and colorectal cancer. Sequencing can quickly and extensively analyze the species, genes and functions of fecal samples, and bacteria⁃host interaction technology can be used to study the mechanism of bacteria on the occurrence and development of diseases from the perspective of experiment, and more accurately determine the relationship between intestinal flora and colorectal cancer. However, some factors, including the differences in DNA extraction, primer deviation, sequencing depth, functional variations at bacterial strain level and the impacts of un⁃identified bacteria, restrict the research progress. With the development of technology, culturomics and organoid have brought new technologies and methods to the study of the relationship between intestinal flora and colorectal cancer, which make up for the deficiency of sequencing technology and experimental technology. This review briefs the relationship between gut microbiota and colorectal cancer, and mainly discusses the research techniques and future development.