HfO2 thin films were prepared by electron beam evaporation technique. Two kinds of post-treatment methods, anneal in oxygen and laser treatment, were employed to treat the samples under the oxygen condition. The procedures of post-treatment and corresponding treatment equipment were introduce and the optical transmittance, absorption and laser induced damage threshold of a HfO2 thin film sample at 355 nm were measured before and after the treatments. The treatment results on reducing absorption and improving the LIDT by above two post-treatment methods were compared, and their working principles were discussed. The experiments demonstrate that laser treatment decreases the sample absorption and improves the LIDT of HfO2 thin films. With one step(50% LIDT), the LIDT of the HfO2 film at 355 nm increases from 13 J/cm2 to 15 J/cm2. With two steps(50% LIDT and 80% LIDT ), the LIDT of the HfO2 film at 355 nm increases from 13 J/cm2 to 17.5 J/cm2, and the damage probability curve translates to a high flux area wholly.