Abstract: Objective:To study the melioration and antioxidation of complexes of soy isoflavones and bovine colostrums (SIBC) on osteoporosis in ovariectomized rats. Methods:The reactive oxygen species scavenging activity of SIBC was detected by biochemical analysis method. Fifty ovariectomized SD rats were randomly divided into five groups:Sham operated control group,ovariectomized group,ovariectomized added low dosage SIBC (117 mg/kg) group,ovariectomized added middle dosage SIBC (233 mg/kg) group,ovariectomized added high dosage SIBC (467 mg/kg) group. The content of femur Ca and femur bone mineral density (BMD),and serum Ca,P,Zn,AKP,blood lipid,and blood and main tissues SOD,MDA were determined after 90 d,respectively. Results:EC₅₀ of scavenging O^-₂·,·OH and H₂O₂ of SCIB were 479.7,1592.3,115.3 μg/mL,respectively. After given the SIBC,the content of femur Ca and BMD of the middle and distal portions of femur of middle and high dosage groups were higher than that the ovariectomized group (p<0.05),respectively. Compared with ovariectomized group,the level of serum TC and AKP decreased significantly (p<0.05 or p<0.01),and the content of serum Ca,Zn and HDL-C increased significantly (p<0.05 or p<0.01) in SIBC groups. The SOD activity of blood,liver,kidney and spleen in high dosage group,and SOD activity of blood and kidney in middle group increased significantly (p<0.05 or p<0.01) than ovariectomized group,respectively. The MDA content of blood,liver and spleen in middle dosage groups,and of liver,kidney in high dosage group decreased significantly (p<0.05) than ovariectomized group. Conclusion:SIBC can remove reactive oxygen species,and prevent the loss of bone Ca and increase BMD,enhance the antioxidant capacity of the body,and improve the osteoporosis by ovariectomy.