Colorectal cancer (CRC) is one of the most common cancers worldwide, especially in western countries. Diet is one of the major factors that contribute to the development of CRC. In recent years, with the development and improvement of social economy in our country, the CRC incidence has been rising with increased trend of young⁃onset cases, which is probably associated with high fat diet, obesity and lack of physical exercises. Studies have shown that high fat diet is closely associated with CRC. High fat diet could alter gut microbiota composition with decreased bacterial diversity along with depletion of Bacteroides and enrichment of Firmicutes. Furthermore, high fat diet could also have an impact on gut metabolites with increased secondary bile acids, fatty acids and sulfide derivants. Studies have demonstrated that excess secondary bile acids could lead to DNA damage and gut inflammation in colon epithelial cells, and also promote proliferation of colon stem⁃like cell⁃Lgr5(+) cells and thus contributing to colorectal tumorigenesis. In this review paper, we will discuss the contribution of high fat diet on colorectal tumorigenesis, the impact of dietary fat on gut microbiota and metabolites, and also dietary strategies for the prevention of CRC.