To explore the physical mechanism of femtosecond laser processing, this paper discusses the mechanism of microscopic damage formation on Al₂O₃ ceramic materials under femtosecond laser irradiation. By combining molecular dynamics and continuous equation simulation methods, the ablation phenomenon caused by femtosecond laser on Al₂O₃ ceramics is analyzed. The movement of atoms on the surface of Al₂O₃ ceramics under femtosecond laser irradiation is compared below and above the ablation threshold, studying the changes in internal temperature, particle number, and pressure of Al₂O₃ ceramics. The results show that when the energy density is higher than the ablation threshold, the target material is fractured under the combined action of temperature and pressure, with the ablation and melting primarily being affected by the heat input time. The research results provide theoretical guidance for the precise processing of dielectric materials with femtosecond laser.