Objective To investigate the effect and mechanism of Humulus lupulus Linn.extract on ovariectomized osteoporosis rats.Methods Sixty female SD rats were randomly divided into sham surgery group,model group,positive control group(estradiol valerate,0.105 mg·kg-1),low-,medium-and high-dose(65.625,131.120,196.875 mg·kg-1)Humulus lupulus Linn.extract groups,with 10 rats in each group.Except for the sham surgery group,other groups had their ovaries removed.After surgery,rats were given drugs once daily by intragastric administration for 90 days.HE staining was used to observe the morphological changes of rat tibia.Bone morphometric parameters were measured,as well as trabecular number(Tb.N),trabecular thickness(Tb.Th),trabecular separation(Tb.Sp),and trabecular area(Tb.Ar)were calculated.Furthermore,we detected the biomechanical status of rat femur,such as maximum load,elastic modulus,and fracture strength.ELISA was used to detect the level of serum estrogen(E2),tartrate-resistant acid phosphatase(TRACP5b),osteocalcin(OC)and bone-specific alkaline phosphatase(BALP)in rats.Serum alkaline phosphatase(ALP)content was measured by using a fully automated biochemical analyzer.RT-PCR and Western Blot were used to detect mRNA and protein expression levels of OPG,RANKL,ERα,ERβ,Wnt16 and β-catenin in rat tibia.Results Compared with the sham surgery group,the tibial trabeculae of the model group was broken,the bone marrow cavity was enlarged,and osteoporotic structure was found.Tb.N,Tb.Th and Tb.Ar of tibia were significantly decreased(P＜0.05),and Tb.Sp was significantly increased(P＜0.05).The maximum load,elastic modulus and fracture strength of femur were significantly decreased(P＜0.05).Serum E2 content was significantly decreased(P＜0.05),and serum TRACP5b,OC,ALP and BALP contents were significantly increased(P＜0.05).The mRNA and protein expressions of OPG,OPG/RANKL,ERα,ERβ,β-catenin and Wnt16 were significantly decreased(P＜0.05),while the mRNA and protein expressions of RANKL were significantly increased(P＜0.05).Compared with model group,positive control group and high-dose Humulus lupulus Linn.extract group had improved the above indexes(P＜0.05).Conclusion Humulus lupulus Linn.extract has a certain preventive and therapeutic effect on postmenopausal osteoporosis,and its mechanism may be related to the regulation of Wnt/β-catenin signaling pathway and the regulation of OPG/RANK/RANKL signaling pathway.