The microstructural and texture evolution of MgO protective films deposited on Si and glass substrates by ebeam evaporation were investigated. MgO films on both types of substrates consisted of a well developed columnar structure showing <111> texture in the cross sectional view and a triangle shape in the plane view. It was found that there is amorphous MgO between each columnar, which occupies 8–25% in the MgO films. The electron energy loss spectroscopy (EELS) spectrum of amorphous MgO showed features of chemical states and electronic structures different from those of crystalline MgO.