Laser damage of fused silica is a critical problem that limits the fluence increase of high-power laser systems. The reaction of plasma processing of fused silica was analyzed. The redeposited layer was removed and scratches of the fused silica were passivated by plasma to increase the laser-induced damage threshold (LIDT). It was found that the deposition generated during the etching process adheres to the surface of fused silica to limit the further increase in the LIDT. The LIDT of fused silica tends to increase and then decrease as fused silica is processed by atmospheric pressure plasma. Accordingly, a competitive evolution for etching and deposition affecting the LIDT of fused silica was established. The etching and deposition relationship analyzed by the model can effectively increase the LIDT of fused silica without deteriorating the original surface of fused silica by choosing an appropriate dwell time.