Objective To quantify the stress and strain of trabecular bone with microdamage/microfracture by using micro-CT and micro-finite element (μFE) analysis, so as to investigate the effects of osteoporosis on relationship between trabecular stress and microdamage/microfracture. Methods Two cylindrical specimens of healthy and osteoporotic acetabular trabecular bones were scanned by micro-CT to build 3D μFE analysis models. The uniaxial compression on two specimens was simulated under frictionless displacement boundary condition. The trabecular stress, trabecular strain, microdamage and microfracture under different apparent strains were calculated through nonlinear μFE analysis. Results For both the healthy and osteoporotic trabeculae under apparent strain of 0.05%-0.50%, the undamaged trabecular stress was under 50 MPa, while the damaged trabecular stress was above 110 MPa. Compared with the osteoporotic trabeculae, the mean stress of the healthy trabeculae was relatively higher, but the maximum stress of the osteoporotic trabeculae was higher. Trabecular damage occurred in both the healthy and osteoporotic trabeculae, while the healthy trabeculae showed more microdamage, and microfracture occurred in the osteoporotic trabeculae. Conclusions Within the scope of apparent strain, the healthy trabeculae can withstand a higher stress with more trabecular microdamage, and microfractures might occur in the osteoporotic trabeculae under the high stress.