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 its sequence and expression characteristics were analyzed. Sequence analysis results showed that ElFAD2 gene full length 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 (pI) 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 Euphorbia 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 Euphorbia lathyris, but the expression of ElFAD2 gene was highest in the seeds 15 days after flowering, and expression level in the leaves and 30 days and 45 days after flowering are equivalent. The expression level was the lowest in roots, stems and flowers. The results facilitated the functional investigations of ElFAD2 gene and provided clues for the analysis of the molecular mechanism of fatty acid synthesis in Euphorbia lathyris.