Abstract: Objective To compare the effects of 6 fatty acids on body weight and blood lipid in hypercholesterolemia mice. Methods A hypercholesterolemia model of C57BL/6J mice was established.Twelve weeks after the animals were fed with high cholesterol diets containing 2% caprylic acid（C8∶0）,capric acid（C10∶0）,palmitic acid（C16∶0）,oleic acid（C18∶1）,α-linolenic acid（C18∶3） or stearic acid（C18∶0）,their blood lipid and lipoprotein levels were measured. Results The body weight increased significantly in different groups 12 weeks after they were fed with different fatty acids,and was significantly higher in animals fed with C8∶0,C10:0 and C18∶1 than in those fed with C16∶0 and C18∶0 group（P＜0.05）.The 6 fatty acids decreased the serum TC and LDL-C levels and increased the serum HDL-C and LDL-C levels.The serum TC and LDL-C levels were significantly lower whereas the serum HDL-C and LDL-C levels were significantly higher in the animals fed with C8∶0,C10∶0 and C18∶3 than in those fed with C16∶0 and C18∶0（P＜0.05）. Conclusion The inhibitory effect of medium chain fatty acids is much better than that of longer chain saturated fatty acids on body weight and blood lipid in C57BL/6J mice.