Objective To investigate the effects of recombinant human osteoprotegerin(rhOPG) on RANKL ,OPG protein expression in alveolar bone tissue of rats with periodontitis to provide the experimental evidence for the application of rhOPG in pe‐riodontitis treatment .Methods Totally 22 Wistar rats were enrolled .The random number table was adopted to select two healthy rats as the healthy group .The rest 20 rats were selected as the experimental group for establishing the rat models of periodontitis , and then subdivided into the experimental control group (n=10) and rhOPG group (n=10) .Rats in the rhOPG group were locally injected by rhOPG 10 mg/kg at periodontal pocket gap of maxillary second molar ,while those in the experimental control group were injected by sterile water for injection at the same site and some volume .The streptavidin‐perosidase(SP) method was em‐ployed to detect the expression of RANKL ,OPG protein in alveolar bone tissue .Results Compared with the healthy group ,the ex‐pression levels of OPG in alveolar bone tissue of rats in the experimental group were lower with statistically significant difference (P<0 .05) ,while the difference of RANKL expression levels between the two groups showed no statistical significance(P>0 .05) . Compared with the experimental control group ,the expression level of OPG protein in alveolar bone tissue of rats in the rhOPG group was significantly up‐regulated ,while that of RANKL protein was significantly down‐regulated(P<0 .05) .The OPG expres‐sion level after treatment in the rhOPG group was markedly enhanced ,while the RANKL expression level was reduced compared with before treatment ,the difference was statistically significant (P<0 .05) .Conclusion rhOPG may regulates the expression of RANKL and OPG in alveolar bone tissue of rats with periodontitis .