Abstract: The(Mg_0.527Al_0.473)(Al_1.758Mg_0.126)O₄(MAO) thin films were synthesized by solid-solid reaction,at 1650℃ and at atmospheric pressure,of the screen printed MgO coatings pre-covered on the 95 wt%Al₂O₃ substrate.The microstructures,phase-structures and surface flashover behavior of the MAO thin films were characterized with X-ray diffraction,scanning electron microscope,energy dispersive spectrometry,X-ray photoelectron spectroscopy and laser confocal microscope.The results show that when it comes to surface insulation,the highly pure MAO coating outperforms the Al₂O₃ substrate with different surface roughness.To be specific,excluding the impact of surface roughness and evaluated with the 8 mm gap of electrodes,the surface flashover voltage the MAO coating was found to be much higher than that of Al₂O₃ plate.