Abstract: In order to understand the chemical etching process of fused silica, the reaction mechanism, processing parameters and the influence of HF etching on the etched surface quality are investigated. The effects of HF concentration, temperature and NH4F concentration on etching rate are obtained by performing the single factor experiment. The surface roughness, morphology, impurity content and damage threshold of the post-etched components are measured, and the experimental results indicate that the etching rate is influenced by a variety of factors, in which the effect of HF concentration is the greatest. The morphology of the HF-etched fused silica surface is complex, containing scratches, pits, impurities and other defects. And the main forms of defects are transverse and longitudinal scratches. The content of the main impurity defect decreases with the increase of etching time. The laser damage test shows that the damage threshold of fused silica is increased by 59.6% through the HF etching process.