Protein methylation is a common post-translational modification in organisms.For a long time,research on protein methylation mainly focused on arginine and lysine,and there were few reports on histidine methylation.However,recent studies have emphasized that histidine methylation is also a widespread and highly conserved modification,occurring at the Nπ and Nτ sites of the histidine imidazole ring,catalyzed by specific protein histidine methyltransferases(PHMTs).Here,we review the history and significant advances in histidine methylation in recent years,particularly highlighting several known histidine methyltransferases.These methyltransferases,through specific molecular mechanisms,are re-sponsible for precise methylation modifications on histidine residues,playing crucial roles in processes such as cell movement,tumor cell proliferation,and protein translation.Additionally,this article discus-ses the research methods for histidine methylation,especially the application of mass spectrometry,which plays a vital role in advancing histidine methylation research.Although the veil of histidine methylation is gradually being lifted,a complete understanding of this modification and its functional mechanisms still poses challenges.Therefore,this article also presents new insights into the current dilemmas in histidine methylation research and future research priorities,hoping to uncover more secrets of histidine methyla-tion in the future.This could expand the protein methylation modification network and provide new per-spectives and strategies for elucidating disease mechanisms and developing new therapeutic approaches.