Objective To observe the effect of conjugated linoleic acids on serum lipids level in rats, according to serum TC,TG,HDL-TC.Methods 50 male Wistar rats were divided into five groups(normal control group, high fat control group,three conjugated linoleic acids groups).The rats were fed with high fat diets and different conjugated linoleic acids oil and four weeks later,serum lipids level are measured. Results Compared with high fat control group,serum TC,TG levels decrease significantly while HDL-TC level kept steady.Conclusion It is suggested that conjugated linoleic acids can reduce serum lipids level.