Abstract: As a key gene in the regulation of long-chain fatty acid biosynthesis, 3-ketoacyl-CoA synthase (KCS) plays an important role in the growth and development of Coix lacryma-jobi L. In this study, the KCS gene was cloned from cDNA of Coix lachryma-Jobi L. and bioinformatics analysis was performed. Results showed that the full length KCS gene was 1 548 bp encoding 515 amino acids. Bioinformatics analysis indicated that the gene encoded a 58 608.12 Da protein with an isoelectric point of 9.20 containing two transmembrane helical structure domains and lacking a signal peptide, with a likely subcellular localization in main plastid membranes. The results of multiple sequence comparisons and evolutionary tree analysis revealed that KCS had three identical conserved sequences and was closely related to KCS from monocotyledons such as Sorghum bicolor, Zea mays, Setaria italica, Panicum miliaceum, Oryza brachyantha, Hordeum vulgare, Aegilops tauschii subsp. Tauschii. We speculated that the evolution of the gene was similar among these plants of the same family. In addition, gene expression analysis showed that the KCS gene was significantly different in Coix lacryma-jobi L. isolates having different lipid content. This work will facilitate further study of the regulatory mechanism of this enzyme in fatty acid synthesis.