Abstract: To investigate effect of different oil ( different proportion of fatty acid composition) on lipid metabolism and hepatic steatosis in rats.Male SD rats in a SPF grade were randomly divided into five groups ( N = 7) .Rats in control group were fed a standard chow diet and rats in model groups were fed high fat diet containing different oil ( lard, palm oil, olive and camellia seeds oil) .In the end of 17th week, body weight and obesity index were measured.After the rats were sacrificed, serum lipids and liver function were analyzed.The livers were weighed and fixed in formalin to make HE stained biopsy.The results showed that chronic high fat diet induced obesity, with significantly increased body weight, fat and Lee's index.The lard group exhibited a slightly higher liver index and the most serious hepatic steatosis compared with the other groups.While the olive oil and camellia seed oil groups revealed light degree of hepatic steatosis.Among the four high fat diet groups, the rats in lard fed group revealed marked hyperlipemia, followed by the palm oil group.There was no significant change in the serum lipids of the camellia seed oil and olive oil diet groups and it showed no difference between camellia seed oil and the control group.The serum SOD, MDA and LPO exhibited the same trend as serum lipids in the four high fat diet groups.The above results suggest that SFA can increase hyperlipemia, thereby causing oxidative stress and leading to liver damage.The amount of UFA along with a proper n-6 /n-3PUFA ratio can regulate lipid metabolism and decrease oxidative stress, consequently reducing hepatic steatosis.