The influences of laser-induced damage threshold by the after-processing of $Al_2O_3$ thin films was investigated. The samples were fabricated at the substrate temperature of $100^{circ}C$, $200^{circ}C$, $300^{circ}C$ and $350^{circ}C$ respectively, and the LIDT were measured by using Nd:YAG laser. After the processing with baking and laser conditioning of the samples, the variation of LIDT was measured. It was found that LIDT was enhanced twice by laser-conditioning process and 1.5 times by baking process. In addition, we measured the chemical properties of the thin film structure before and after the processing by using XPS.