Abstract: The mechanism of action of excimer laser (ArF:193nm 8ns) on cornea is very important in the ablation refractive surgeries such as laser in situ keratomileusis(LASIK)and photorefractive keratectomy(PRK).In this paper,we analyze photoablation model and photophysical model that describe the mechanism of action of excimer laser (ArF:193nm 8ns) on cornea,elicit the relationship between the energy density and the ablation depth.The factors that would influence the predictability and stability of the photorefractive surgery outcome are also investigated.Then the scanning algorithm can be optimized.The results have been directly applied to the ophthalmic excimer laser system and obtain satisfactory effect in diopter correction.