The study was aimed to investigate the effects and mechanism of manganese superoxide dismutase (MnSOD) on tert-butyl hydroperoxide(t-BHP) induced apoptosis in human bone marrow mesenchymal stem cells (MSCs). The MnSOD gene was cloned from human fetal liver by RT-PCR. The MnSOD recombinant plasmid was transfected into MSCs stably by lentiviral system. The efficiency of virus transfection was identified by expression of enhanced green fluorescence protein (EGFP) analyzed by fluorescence microscope, then MSCs were sorted by fluorescence-activated cell sorting (FACS) according to strong EGFP expression. MnSOD expression was detected by RT-PCR and Western blot. Transfected cells were then treated with different concentration of t-BHP, and the features including cell viability, senescence-associated β-gal activity, and apoptosis were evaluated. Our data demonstrated that overexpression of MnSOD could promote MSCs viability by inhibiting apoptosis or cellular senescence. Furthermore, apoptosis related genes p53 and PUMA were down-regulated. Therefore, these results indicated that overexpression of MnSOD in MSCs could protect against t-BHP induced apoptosis.