To study the effects of miR-22 on the proliferation and the apoptosis of osteosarcoma MG-63 cell line and to explore the potential molecular mechanism that miR-22 regulates this biological process. Quantitive real-time polymerase chain reaction (RT-qPCR) was performed to explore the miRNA level of miR-22. The MG-63 cell line was infected with miR-22 mimics for establishment of miR-22 overexpression. Non-infected cells were in blank group and cells infected with empty vector were served as negative control (NC group). MTT assay was conducted to measure cell viability. The cell cycle and apoptosis were explored using flow cytometry and the apoptosis-related markers were detected by western blotting. RT-qPCR results revealed that the miR-22 miRNA level in the MG-63 cells was significantly lower than that in osteoblasts (P<0.05). MTT assay showed that the MG-63 cells infected with miR-22 mimics exhibited markedly decreased proliferation ability compared with blank and empty vector (NC) groups. Next, we found that overexpression of miR-22 remarkably increased the apoptosis of the MG-63 cells, evidenced from the flow cytometry results and elevated Bax and reduced Bcl-2. Furthermore, results revealed that percentage of the cells at G0/G1 phase in miR-22 mimic group (66.75 +/- 3.67%) was significantly higher than blank (52.9 +/- 2.58%) and NC (50.5 +/- 2.45%) groups. miR-22 attenuated the proliferation and induced the apoptosis of the MG-63 cells via promoting G0/G1 cell cycle arrest. Thus, miR-22 may have the potential to be a novel therapeutic in treatment of osteosarcoma.