Oxygen diffusion in MgO stabilized zirconia has been studied by molecular dynamics simulation method with MOLDY software. The results illustrate that oxygen diffusion in MgO stabilized zirconia can be decided by temperature and amount of MgO. Both increase of amount of MgO and temperature in the system may promote the oxygen diffusion. Further increase in temperature is helpful to the oxide ions diffusion. There is always a maximum value of oxygen diffusion coefficient, which is represented by the slope of MSD curves, corresponding to a certain amount of MgO. In MgO stabilized zirconia, the most suitable doped amount of MgO exists in a range , which is decided by the working temperature of MgO stabilized zirconia.