Abstract: The magnesium oxide, due to its high secondary electron emission coefficient, is suitable as a secondary electron emission material for the preparation of multi-stage amplification devices. In this paper, the high-quality magnesium oxide films and the titanium-doped magnesium oxide films are prepared by the magnetron sputtering, and the morphology of the films is characterized. In addition, the secondary electron emission multiplication characteristics of the films used in the MgO film electron multiplier are studied. The gain characteristics and the gain reduction of the electron multiplier are also analyzed. It is shown that the increase of the voltage or the current of the high voltage source can both increase the current gain multiple of the electron multiplier; the titanium doping, for example, the Ti-doped MgO film in comparison with the pure MgO film, can not only increase the gain of the electron multiplier, but also extend the working life of the multiplier more than two times.