Abstract: According to exon 5 sequences published by GenBank of 2, 4-dienoyl-CoA reductase 1(DECR1) gene of bovine（NP_001068891）, one pair primer was designed to amplifiy exon 5 of DECR1 gene by using PCR technique for three sheep populations including of German MuttanMerino sheep, Dorper sheep and Texel sheep, the single nucleotide polymorphism of three sheep populations were detected by PCR-SSCP, and compared and analyzed with other species of chicken, rat, sheep, pig, human, bovine, rabbit, dog from GenBank. The results showed that the size of DECR1 gene exon 5 was 137 bp, SNPs was not found in exon 5 of DECR1 gene by PCR-SSCP. By means of sequence homology aligment between sequence of exon 5 of sheep DECR1 gene and others species, the results showed that homology of different species DECR1 gene was 81.02% to -97.08%, the highest similarity was 97.08％ between sheep and bovine. The molecular phylogenetic tree constructed by DECR1 gene exon 5 sequences showed that sheep clustered with bovine firstly，and secondly with rabbit and dog, and then human and pig. This results indicated that sheep had the most nearest relative relationship with bovine, but the far-thest with chicken. It was consistent with the orthodox taxonomic results, and DECR1 gene was very conservative in the progress of animal evolution

Key words: sheep; DECR1 gene; exon5; sequence; SNP