One microsomal ω3 fatty acid desaturase gene fragment and two plastidial ω3 fatty acid desaturases cDNA and genomic sequences, designated CtFAD3, CtFAD7 and CtFAD8 have been isolated from safflower (Carthamus tinctorius L.) and submitted to GenBank. Our Blast searches of the deduced amino acid sequences revealed that the similarities of CtFAD7 and CtFAD8 with other plant plastidial ω3 fatty acid desaturases were 61-79 % and 63-78 %, respectively, while CtFAD3 showed higher similarities to other plant microsomal ω3 fatty acid desaturases, 60-93 %. The deduced amino acid sequences of these genes showed three histidine boxes (HDCGH，HXXXXXHRTHH and HVIHH) characteristic of all membrane-bound desaturases, and CtFAD7 and CtFAD8 possess a putative N-termianl signal peptide, 56 and 27 aa respectively. In hydropathy and transmembrane analysis showed that the encoded polypeptides contain four putative hydropathy regions and transmenmbrane one to three times. Protein second-structure indicated that safflower ω3 fatty acid desaturase were composed by α-helix and β-sheet. Compared with the genome structures of safflower CtgFAD7 and CtgFAD8 and other plant plastidial ω3 desaturase genes, all the sequences contained 8 extons and 7 introns. The sequence and size of introns in all plant plastidial ω3 desaturase genes exhibited a wealth polymorphism between species, while the sizes of the internal 6 exons (from 2nd to 7th) were conservative. Comparing the location of the introns revealed that the intron occurs were the conserved regions of the enzyme. We speculated that these introns play an important role in assuring the gene function in the species evolutionary process.