In order to study the regulation mechanism of ElFAD2 gene on the synthesis of unsaturated fatty acids in Euphorbia lathyris, this study obtained the ElFAD2 gene sequence based on the transcriptome database, and analyzed its sequence and expression characteristics. Sequence analysis results showed that the full length of ElFAD2 gene was 1 907 bp and the ORF was 1 152 bp, encoding 383 amino acids, containing a typical fatty acid desaturase domain. The isoelectric point of ElFAD2 protein was 8.08 and belonged to a stable protein with 4 transmembrane regions and 3 conserved histidine clusters. The phylogenetic tree analysis showed that E. lathyris had a closer relationship with Triadica sebifera from Euphorbiaceae. Realtime PCR analysis revealed that the ElFAD2 gene was expressed in different organs of E. lathyris, but the expression of ElFAD2 gene was the highest in the seeds of 15 days after flowering, and the expression levels are equivalent in the leaves and seeds of 30 days and 45 days after flowering. The expression level was the lowest in roots, stems and flowers. The results facilitated the functional investigation of ElFAD2 gene and provided clues for the analysis of the molecular mechanism of fatty acid synthesis in E. lathyris.