In order to improve the laser damage performance of ultraviolet fused silica, a method which combines magneto-rheological finishing (MRF) with HF acid etching process was proposed to reduce crack and contamination defects in the machining process of traditional processing method. MRF can effectively remove the crack defects with its unique shear and removal principle in traditional machining process while not produce new crack defect. HF acid etching process can effectively reduce metal elements contamination. The experimental results show that fused silica sample using the combined process has a better antidamage performance. Damage density reduced from 0.2mm^-2 to 0.008mm^-2 under the laser flux irradiation of 7J/cm²?3ω and from 1mm^-2 to 0.1mm^-2 at the irradiation of 8J/cm²?3ω.