ObjectiveThe biosynthetic pathways of benzylisoquinoline alkaloids（BIAs） in Nelumbo nucifera are of great theoretical and economic value. In this paper， N. nucifera O-methyltransferase（NnOMT） and N. nucifera N-methyltransferase（NnNMT） gene families were identified and analyzed by bioinformatics in order to facilitate the biosynthetic pathway of BIAs in N. nucifera. MethodBased on the whole genome of N. nucifera， UniPort and National Center for Biotechnology Information（NCBI） databases were used to identify the NnOMT and NnNMT gene families of N. nucifera， and analyze their physicochemical properties and subcellular localization， then TBtools， MEME， MEGA 11.0， FigTree 1.4.4 and other tools were used to analyze the phylogeny， sequence characteristics， gene structure， functional annotation and cis-acting elements of NnOMT and NnNMT genes identified in the previous stage. ResultA total of 61 NnOMT and NnNMT genes were identified in this paper， the number of amino acids encoded by these genes ranged from 168 aa to 580 aa， the isoelectric point ranged from 4.76 to 9.16， and the relative molecular weight ranged from 18 699.52 Da to 64 934.53 Da， most of which showed acidic and mostly hydrophilic proteins. There were 10 conserved motifs， Kyoto Encyclopedia of Genes and Genomes（KEGG） analysis enriched a total of 12 pathways， including metabolism， biosynthesis of phenylpropane and isoquinoline alkaloids， etc. And Visualization of Gene Ontology（GO） enrichment results showed that 61 NnOMT and NnNMT genes were annotated to 32 items， which included 16 molecular functions［such as reduced nicotinamide adenine dinucleotide（NADH） activity and exopeptidase activity］ and 16 biological processes（such as metabolic process of carbon tetrachloride， anaerobic carbon tetrachloride metabolic process and responses to exogenous biological stimuli）. There were a variety of cis-acting elements in the promoter regions of NnOMT and NnNMT genes， mainly promoter and enhancer regions element， light responsive element and methyl jasmonate responsive element. ConclusionIn this study， a comprehensive bioinformatics analysis of 61 NnOMT and NnNMT genes is carried out based on the genome data of N. nucifera， which lays a foundation for research on the gene structure and function of NnOMT and NnNMT gene families， and provides a reference for biosynthetic pathway elucidation of BIAs in N. nucifera.