The ablation of the aluminum oxide ceramics is theoretically investigated using the femtosecond laser with multiple pulses in this paper. There is now a growing interest in laser micromachining using pulses of femtosecond duration. Among its advantages is the possibility machining hard and brittle materials that can be easily damaged by conventional drilling and cutting procedures. Femtosecond laser micromachining of ceramics can produce nanoscale patterns due to the laser pulse duration shorter than the relaxation time of heat transport among phonons. Laser ceramics ablation possesses another features, which include the phase transition from solid to vapor occurs without melt, the strong dependence of the thermophysical parameters and the volumetric absorption. The thermal process of femtosecond laser ceramics ablation is modeled by the heat conduction equation considering material evaporation and plasma plume absorption. The ablation depth per pulse and squared crater diameter predicted by this work are compared with the available experimental data. The predictions of temperature field and ablation shape in the aluminum oxide ceramics are also shown in this study. (C) 2011 Elsevier B.V. All rights reserved.