Abstract:The present study was carried out to research the contents of fatty acid in longissimus dorsi from Ningxia Tan sheep，Small Fat-tail Sheep and Tan Han hybrid sheep，and to evaluate the effects of breed on fatty acid composition for major breed in Ningxia region.18 trial sheep with similar feeding and management conditions，ages（about five-month），and healthy were selected and divided into three groups according to the species including Tan sheep，Small Fat-tail Sheep，and Tan Han hubrid sheep，and six sheep for each group were taken as repetition.All sheep were slaughtered after trial，and the longest muscle samples were collected and the absolute amount of fatty acids in the meat was determined.Fatty acids in mutton tissues are mainly oleic acid （C18：1），stearic acid （C18：0）and palmitic acid （C16：0），and these three fatty acids approximately accounted for more than 85%of muscle fatty acid content.In addition，the content of unsaturated fatty acids in lamb was also higher than saturated fatty acids，especially for monounsaturated fatty acids.It was showed that the highest total fatty acid content in Tan sheep was 90.525 g/kg，but there was no significant difference among breeds（P>0.05）.Small Fat-tail Sheep had the highest saturated fatty acid content of 40.449 g/kg；the highest content of unsaturated fatty acids in the mutton was 55.33 g/kg，the contents of oleic acid （C18：1）and γlinoleic acid （C18：2n6）were significantly higher than that of Small Fat-tail Sheep and Tan Han hynrid sheep（P<0.05）.The analysis of the composition of fatty acids in lambs of different breeds showed that the fatty acids in Tan mutton were abundant and had certain varietal advantages，especially the high content of oleic acid（C18：1）and γ-linoleic acid（C18：2n6）in functional fatty acids.This also provides a theoretical basis for Tan sheep's high quality lamb production.