The present review suggests that expression of the methyltransferase METTL3 is significantly increased in various gastrointestinal cancer (GC, CRC, HCC, and PC) cells compared to normal cells and acts as an oncogene to promote the progression of gastrointestinal cancer; METTL3 can serve as a clinical diagnostic and therapeutic target. This evidence concerns the gene METTL3 and hepatocellular carcinoma.