Abstract: Long-chain acyl coenzyme A synthetase (LACS) is one of the important catalytic lipid metabolic enzymes in peanut plants. To understand the mechanism of the fatty acid metabolism in peanut (Arachis hypogaea L.), the cDNA of LACS6 gene was cloned by RT-PCR (GenBank accession number:KU301860). Its structure was analyzed, homology with other plants compared, and mRNA expression in different tissues obtained using real-time PCR. The results showed that the cDNA was 2,116 bp including an open reading frame of 2,088 bp, encoded 695 amino acids, and had 23 exons and 22 introns. Its amino acid sequence alignment showed a conserved domain of eukaryotic long-chain fatty acid CoA synthetase, as well as conserved activation and binding sites. The homologies of LACS6 gene with the genes from Cicer arietinum, Vigna radiate, Glycine max, Prunus mume and others were between 79% and 87%. The evolutionary tree indicated that the gene was close to those from leguminous plants, such as chickpeas. The real-time PCR analysis showed that it was differentially expressed in the ovary stalks, roots, stems, leaves, flowers and kernels on a peanut plant. The ovary stalks and flowers had the highest expression among all,and with significant differences,The order of expression ranked as flowers > ovary stalks > leaves > kernels > stems > roots. The information obtained would benefit further studies on the fatty acid metabolism and quality improvement for peanut.