Objective To evaluate the efficacy of BSYJF on raising the quality of cortical bone of femur in osteoporotic rat model induced by ovariectomy and its mechanism on improving biomechanical properties of cortical bone. Method Forty female Wistar rats were divided randomizedly into four groups: Sham control group(GA), Ovx control group(GB), BSYJF group(Ovx+BSYJF,GC) and BML Group(Ovx+BML, GD). The time point of administering drug(BSYJF or BML) to the rats was 90 days after ovariectomy. The time point of sacrificing was 180 days later. After sacrificing, macroscopic geometry structure, bone mineral density and bionechanical properties of three-point bending (structural mechanical property and material mechanical property) of femur were determined. Results In GB, the dirmeter of medullary canal was enlarged significantly (P<0.05) and the thickness of cortical bone decreased significantly ( P <0.05), respectively vs GA; in GC and GD, there was no significant change of the diameter but the thickness of cortical bone all was enlarged olveously (P<0.05), respectively vs GB. The bone mineral density in GB were not decreased significantly as compared with GA also in GC compared with GB. In GB the parameters of structural mechanical property(maximum load. stiffness and energy) and the parameters of material mechanical property(maximum stress and elastic modulus) were decreased significantly (P<0.05), respectively compared with GA. Stiffness and elastic modulus in GC were increased significantly (P<0.05) but not in GD (P<0.05) and other parameters of mechanical properties in the two groups (GC and GD) were all increased sinificantly (P<0.05), respectively compared with GB. Conclusion BSYJF can raise the quality of cortical bone of femur in the rat model induced by ovariectomy. In improving biomechanical properties of cortical bone, BSYJF has the same partial mechanism, which can modify the macroscopic geometry structure of cortical bone as BML. But BSYJF has another different mechanism, which can up-regulate stiffness and elastic modulus of cortical bone without increasing bone mineral density.