Objective : To reveal the role of periodontal ligament stem cell-derived exosomes (PDLSC-Exos) in orthodontic bone remodeling, in order to provide new therapeutic strategies for orthodontic tooth movement (OTM). Methods : This study has been reviewed and approved by the Ethics Committee. Healthy periodontal ligament tissues from clinical orthodontic reduction extractions were collected, and periodontal ligament stem cells (PDLSCs) were isolated and cultured. When cultured to the third generation, their self-renewal ability and multidirectional differentiation potential were detected. PDLSC-Exos were isolated and purified by gradient centrifugation and identified by transmission electron microscopy, immunofluorescence, ZetaView, and nanoflow cytometry. The co-culture of 10 μg/mL PDLSC-Exos and PDLSCs (PDLSCs+Exos) induced osteogenic differentiation to evaluate the effect of osteogenesis. Bone marrow-mononuclear cells (BMMs), promoted by osteoclast differentiation [30 ng/mL macrophage colony stimulating factor (M-CSF) + 50 ng/mL receptor activator of nuclear factor-κ B ligand (RANKL)], and then were treated with 10 μg/mL PDLSC-Exos to assess the effect on osteoclasts. We established a rat model of OTM, and 50 μg/mL PDLSC-Exos was injected locally into the periodontal ligament before we established the model (OTM + Exos), every 2 days for 14 days. Alveolar bone remodeling was analyzed by micro-CT, and alveolar bone osteoclasts were analyzed by immunohistochemistry and immunofluorescence. Results: The isolated and purified PDLSCs met the basic characteristics of mesenchymal stem cells, and PDLSC-Exos had typical characteristics of extracellular vesicles. PDLSCs-Exos significantly promoted the osteogenic differentiation of PDLSCs, and promoted the osteoclast differentiation and bone resorption activity of BMMs (P < 0.05). The rate of alveolar bone remodeling in rats with local periodontal injection of PDLSC-Exos was significantly accelerated, and the tooth movement distance was significantly increased (P < 0.05); immunohistochemistry results showed that PDLSC-Exos promoted the differentiation of osteoclasts (P < 0.05). In addition, immunofluorescence showed that PDLSC-Exos co-localized with osteoclasts, indicating that PDLSC-Exos may promote osteoclast differentiation in vivo. Conclusion PDLSC-Exos accelerate the rate of orthodontic bone remodeling by promoting osteogenic differentiation of PDLSCs and osteoclast differentiation of BMMs, thereby accelerating OTM.