〔Abstract〕 Objective To investigate the killing effect of Cold atmoshperic plasma on human osteosarcoma cell line MG63 and its possible mechanism. Methods The proliferation inhibition effect of Cold atmoshperic plasma on MG63 cells was determined by MTT assay and colony formation assay. The effect of Cold atmoshperic plasma on the morphology of MG63 cells was observed under a microscope. Apoptosis was detected by flow cytometry, and the changes in expression of apoptosis related proteins was detected by Western blot. Results Microscopic observation showed that Cold atmoshperic plasma could induce the shrinkage of MG63 cells. In both MTT and colony formation experiments, Cold atmoshperic plasma showed significant proliferation inhibition effect on MG63 cells in a dose-dependent manner. The cellular analysis showed that Cold atmoshperic plasma caused inhibition of cell proliferation by inducing apoptosis. Western blot showed that Cold atmoshperic plasma could induce the expression of apoptotic proteins in a dose-dependent manner. Conclusion Cold atmoshperic plasma has a significant killing effect on MG63 cells, which may be related to the induction of apoptosis.