Abstract: Objective：To investigate the effect of TNF-α in the osteoblastic differentiation of bone marrow mesenchymal stem cells (BMMSCs) derived from postmenopausal osteoporosis. Methods：Established an ovariectomized mouse model. Micro-CT was used to examine the bone in the femurs of the mice. The osteogenesis of BMMSCs derived from sham and OVX mice were investigated by ALP activity, ALP and Alizarin Red staining. Osteogenic genes Runx2 and Osterix were determined by real time RT-PCR and Western blot. TNF-α levels in serum were examined via Elisa assay. Results：The BMD of OVX group was significantly lower than that of Sham group. The osteogenic differentiation of OVX-BMSMCs was inhibited compared with Sham-BMMSCs. TNF-α levels were increased in OVX mice. TNF-α impaired BMMSCs osteogenic differentiation. TNF-α neutralizing antibody was injected via caudal vein in OVX mice and TNF-α levels were reduced. Calcein double labeling and Micro-CT showed bone formation were higher in OVX mice which were treated with TNF-α neutralizing antibody. Conclusions： TNF-α was a key inflammatory cytokine that inhibited osteogenic potential of BMMSC derived from estrogen deficiency-induced osteoporosis. Injection of TNF-α neutralizing antibody in vivo can increase bone formation of OVX mice. TNF-α impaired osteogenic differentiation may be one of mechanisms in estrogen deficiency-induced osteoporosis.