Methionine is the primary limiting amino acid in maize-soybean meal diets for livestock and poultry. An imbalance in amino acids can inhibit protein synthesis in animals， thus affecting the quality of meat and milk. To analyze the regulatory mechanism governing methionine accumulation in maize grains， this study used homologous cloning strategy to identify a candidate gene， ZmTS1 （Threonine Synthase 1）， which affects methionine content. Methionine content in Zmts1 mutant seeds increased by 60%. SDS-PAGE analysis revealed that the methionine residue-rich 10 kDa-δ alcohol-soluble protein in mature Zmts1 mutant kernel was significantly elevated compared to the wild type， confirming that this gene could significantly increase methionine content in maize kernels. Bioinformatics analysis indicated that the gene contained a threonine synthase structural domain and the encoded protein was hydrophilic. Transcriptome analysis revealed 1144 differentially expressed genes associated with methionine metabolism， of which 571 and 573 were up-regulated and down-regulated， respectively. GO and KEGG enrichment pathway analysis showed that the differentially expressed genes were mainly involved in the biosynthesis and metabolism of amino acids. qRT-PCR was used to further analyze seven key candidate genes that may be involved in methionine metabolism pathway. The transcriptional patterns revealed by both in RNA-Seq and qRT-PCR implied indirect functions of these genes in the methionine metabolic pathway. This study provides new germplasm resources for breeding methionine-rich maize， and offers a theoretical basis for understanding methionine regulation mechanisms in maize.