Objective To observe the three dimensional micro-architecture of osteoporosis and non-osteoporosis cancellous bone and its effect on bone strength. Methods 16 adult female sheep were randomly divided into 2 groups: sham-operate group with only ovary-reveal (8 sheep) and OVX group with ovarietomy (8 sheep). During the operation, all sheep underwent dual energy x-ray absorptiometry (DEXA) for the lumbar vertebrae. 12 months after operation, all sheep were sacrificed and underwent DEXA scan for lumbar spine. The cylindrical trabecular bone of vertebral body was harvested by trepan and reconstructed by micro-CT. In biomechanical evaluation, the axial compressing tests were accomplished on the cylindrical bone. Result The BMD in OVX group decreased significantly than that in Sham group (P<0.01). In micro-architecture analysis, the BS/BV, Tb. Th and Tb. N in OVX group also decreased significantly, while the Tb. N and BVF increased (P<0.01). In biomechanical testing, the maximum compressing strength of trabecular bone in OVX group was lower than that in sham group. The Tb. Th was highly correlated with maximum compressing strength of trabecular bone (r=0.945, R^2=0.886). The BVITV (r=0.783, R^2=0.586) and BSITV (r=0.643, R^2=0.372) were correlated with the maximum compressing strength. Conclusion The altering micro-architecture of trabecular bone has effect on its mechanical properties. There is some correlation between micro-structure parameters and bone strength.