Abstract: The fatty acid composition of peony seed oil from Western Hunan was testing by GC-MS method.The assist effect for lipid lowering was testing through the 50 human feeding trials.The result indicated that the compositions of peony seed oil from Western Hunan were: palmitic acid of 6.04%, stearic acid of 1.84%, oleic acid of 25.20%, linoleic acid of 28.65% and linolenic acid of 37.41%.The total concentration of polyunsaturated fatty acid reached to 91.26%.Peony seed oil from Western Hunan could lower the TC ( serum total cholesterol) , TG ( triglyceride) , LDL-C ( low density lipoprotein cholesterol) levels of human subjects obviously and the lower range were 13.20%, 35.98%, 10.72%, respectively, with statistically significant in difference, and the total effective rates could reach to 70.73%, 81.40%, 66.67%, respectively, but no effect on HDL-C ( high density lipoprotein cholesterol) levels, which indicated the peony seed oil had better assisting for lipid lowering.