Some essential trace elements were reported to be involved in the normal bone metabolism. Nowadays rare earth elements are widely used in many fields and more and more rare earth elements enter the environment and food chains. They are enriched in bone and difficult to be excreted. Because the similarity between rare earth ions (Ln(3+)) and Ca2+, they will intervene and regulate bone formation and remodeling. On one hand, rare earth are presumed to be drug candidates for bone disease; on the other hand, they have negative effects on bone metabolism. So the safety of rare-earth-based drugs deserves an answer. We review the effect of rare earth ions on bone metabolism as the following three aspects: (1) effect of rare earth ions on differentiation and function expression of osteoblasts and osteoclasts; (2) effect of rare earth ions on the osteogenic and adipogenic differentiation of bone marrow stromal cells; (3) effect of rare earth ions on bone mineral phase of animals. In addition, the scarcities and future developing perspectives in this field are also discussed.