Abstract: The purposes of this study are to investigate the effects of bovine and sheep grease on the blood physiological indexes and organ morphology of mice and explore the partial immune function of bovine and sheep grease, and then lay a foundation for the development and utilization of animal fat products. Thirty male Kunming mice with body weight of 28-30g were chosen, they were divided into control group, sheep grease group and bovine grease group, and they were given by gavage with saline, the tail oil of sheep and the lipid of bovine kidney, respectively. After 30 days, blood was taken from the eyes and the blood physiological and biochemical indexes were measured. Tissue samples of heart, liver, spleen, stomach and kidney were collected to be weighed and paraffin sections were made to observe the changes of tissue structure. The results showed that the liver coefficient of sheep grease group was significantly higher than that of the saline group (P <0.01), the coefficient of gastric organs was significantly higher than that of the saline group (P <0.05), the coefficient of heart, spleen and kidney had no difference with that of the saline group (P >0.05). The coefficients of heart and liver were significantly higher in bovine grease group than those in saline group (P <0.01), the coefficients of spleen, kidney and stomach had no difference with that of the saline group (P > 0.05). The two greases caused a significant increase of white blood cells, and decreased erythrocytes in mice. Sheep grease increased the number of platelets, while bovine grease increased the number of platelets obviously. In the paraffin section, the fat in the hearts of sheep grease group and bovine grease group increased, a few of cardiac muscle cells showed steatosis, the number of fat cells in the stomach and perirenal area increased, and there was no obvious change in the liver and spleen. The results indicate that bovine and sheep grease have a certain immune function.