Surface defect induced by machining in fused silica is the main causation weakening anti-laser-damage ability in actual application. The technology using local high temperature CO2 laser treatment repairing surface characteristic defect in fused silica is developed. It is presented that scale of surface defect is decreased and microcosmic interior structure quality of defect is improved after CO2 laser repairing. Through measuring the damage-threshold of repaired defect, is discovered that damage threshold of scrape-line with depth 200 nm is increases about 100 percent, and the damage growth threshold and anti laser radiation times of initial damage pit with diameter 10-100 μm is increased obviously too. It proves that the method using CO2 laser treatment repairing surface defect in fused silica can improve anti-damage ability and the life extending is doable.