ObjectiveTo explore the possible mechanism of Osteoking （OK） on postmenopausal osteoporosis （PMOP）. MethodForty adult female mice were randomly divided into a sham operation （Sham） group， osteoporosis model （OVX） group， estradiol intervention （E₂） group， and OK group， with 10 mice in each group. The modeling was completed by conventional back double incision ovariectomy， and the corresponding drugs were given one week later. After 12 weeks， the body mass and uterine index of mice were measured， and the pathological changes of bone tissue and the number of osteoclasts （OCs） were determined by hematoxylin-eosin （HE） and tartrate-resistant acid phosphatase （TRAP） staining， respectively. Bone mineral density （BMD）， trabecular number （Tb.N）， trabecular separation （Tb.Sp）， and bone volume fraction （BV/TV） were measured by microcomputed tomography （Micro-CT）. The maximum load of the femur was detected by a three-point bending test. The contents of tumor necrosis factor-α （TNF-α） and bone resorption marker C-terminal telopeptide of type Ⅰ collagen （CTX-1） were measured by enzyme linked immunosorbent assay （ELISA）. The protein expression levels of nuclear factor-kappa B p65 （NF-κB p65）， phosphorylated nuclear factor-kappa B p65 （p-NF-κB p65）， nuclear factor kappa B inhibitor alpha （IκBα）， phosphorylated nuclear factor kappa B alpha （p-IκBα）， nuclear factor of activated T cells 1 （NFATc1）， and proto-oncogene （c-Fos） were detected by Western blot. The mRNA expressions of OCs-related specific genes matrix metalloproteinase-9 （MMP-9）， NFATc1， TRAP， cathepsin K （CTSK）， and c-Fos were detected by real-time fluorescence quantitative polymerase chain reaction （Real-time PCR）. ResultCompared with the Sham group， the uterine index decreased significantly in the OVX group， and the body mass （BMI） increased significantly. The structure of bone trabeculae was completely damaged， and the number of OCs increased. BMD， Tb.N， BV/TV， and maximum load decreased， while Tb.Sp was up-regulated. The levels of TNF-α and CTX-1 in serum were up-regulated. The protein expressions of c-Fos， p-NF-κB p65/NF-κB p65， NFATc1， and p-IκBα/IκBα were increased. The mRNA expressions of NFATc1， c-Fos， CTSK， TRAP， and MMP-9 were up-regulated （P<0.05， P<0.01）. Compared with the OVX group， the body mass of the OK and E₂ groups decreased， and the uterine index increased. The bone trabeculae increased， and the number of OCs decreased. BMD， Tb.N， BV/TV， and maximum load increased， while Tb.Sp decreased. The levels of TNF-α and CTX-1 in serum were decreased. The protein expressions of c-Fos， p-NF-κB p65/NF-κB p65， NFATc1， and p-IκBα/IκBα were decreased， and the mRNA expressions of NFATc1， c-Fos， CTSK， TRAP， and MMP-9 were decreased （P<0.05， P<0.01）. ConclusionOK can inhibit the NF-κB/NFATc1 signaling pathway and reduce bone mass loss by reducing the level of inflammatory injury factors in PMOP mice， which is one of the mechanisms for treating PMOP.