N7-methylguanosine (m7G) is a common post-transcriptional modification of RNA that plays an important role in RNA processing, metabolism and function and is mainly regulated by the methyltransferase 1 (METTL1) and WD repeat domain 4 (WDR4) complexes. Several studies have shown that the METTL1/WDR4 complex promotes or inhibits the progression of many tumours, including head and neck tumours, lung, liver, colon, bladder and esophageal squamous cancers, which are dependent on m7G methylation modification of tRNA or miRNA. Therefore, METTL1 and m7G modification can be used as biomarkers or potential intervention targets, providing a new direction for early diagnosis and treatment of tumors. This article will mainly discuss the mechanism and corresponding research progress of METTL1 in tumorigenesis through m7G.