ROS　produced　under　oxidative　stress　are　crucial　for　osteoclast　differentiation.　Metallothionein　(MT)　is　a　ROSscavenging　molecule.　As　a　member　of　MT　family,　MT2　can　clear　ROS　in　osteoclast　precursors　(OCPs)　and　contributes　to　osteoclast　differentiation.　RANKL　can　promote　OCP　autophagy.　Given　the　molecular-degrading　effect　of　autophagy,　the　relationship　between　RANKL-dependent　autophagy,　MT2　and　ROS　during　osteoclast　differentiation　is　worth　exploring.　We　depended　in　vitro　RANKL　administration　and　RANKL-overexpressing　(TgRANKL)　mice　to　observe　the　effects　of　RANKL　on　ROS　production,　MT2　protein　expression,　Beclin1　expression　and　autophagic　activity　in　OCPs.　Spautin1　was　used　to　investigate　the　relationship　between　Beclin1-dependent　autophagy　and　RANKL-regulated　MT2　expression.　Osteoclast-targeting　MT2-cDNA-AAVs　were　applied　to　assess　the　therapeutic　effect　of　MT2　on　Tg-RANKL-related　bone　loss.　The　results　showed　that　RANKL　promoted　ROS　production　but　reduced　MT2　protein　expression　in　OCPs.　RANKL　also　enhanced　Beclin1　expression　and　LC3puncta　abundance.　Decreased　Beclin1　expression　with　spautin1　blocked　RANKL-increased　ROS　production　and　osteoclast　differentiation　and　recovered　RANKL-decreased　MT2　expression.　MT2　selective　overexpression　with　CD11b-promoter-MT2-cDNA-AAVs　attenuated　ROS　production　and　osteoclastogenesis　in　Tg-RANKL　mice　and　improved　bone　loss.　Overall,　RANKL　can　reduce　MT2　protein　expression　through　Beclin1-dependent　autophagy,　thereby　promoting　ROS　production　and　osteoclast　differentiation;　this　suggests　that　MT2-overexpressing　small　molecule　drugs　have　the　potential　to　treat　RANKL-related　bone　loss.