In order to improve the damage threshold of fused silica chip, the bare fused silica chip with small aperture etched by hydrofluoic acid is scanned by 10.6 μm CO2 laser with a raster scaning form, and the laser power increases periodically. Results show the surface micro-topography of the pretreated chip is greatly improved. The means of S:1 method is used to measure its damage threshold. Under the conditions of moderate laser polishing, the zero probability damage threshold of the fused silica chip is increased by 30%, and no negative effect on transmission wavefront is introduced. The validity of CO2 laser pretreatment enhancing the bare fused silica chip damage resistant is proved.