Orthodontic tooth movement is a dynamic process, which includes bone resorption on the pressure side and osteogenesis on the tension side. Bone mesenchymal stem cells (BMSCs), which are force-sensitive cells, have potentials for differentiation into cells with various types. Their biological characteristics can change functionally according to the appropriate stimulation in vitro, in order to reach the optimal demand of the stimulation. Many signal pathways are involved in osteogenesis. Signal transducers and activators of transcription 3 (STAT3) is a ubiquitously expressed transcription factor, mediating cell proliferation, differentiation, survival, apoptosis and cellular immunity. It has been reported that STAT3 can regulate the differentiation process of BMSCs into osteoblasts. This paper summarizes the recent progress about effect of STAT3 on bone differentiation of BMSCs and the possible mechanism.