The energy of the laser milling was input to the sample surface in the mode of local heat, which can cause the uneven and unstable of the temperature field during the laser milling. Take the laser milling on the Al₂O₃ ceramic materials for an example, the article set up the 3D finite element simulation model of the laser milling temperature field. The heat moving of the laser milling was simulated by the APDL language of the ANSYS software. The result of the simulation shows that the temperature of the center spot of the back track is higher than the front track with the process of the laser milling. The greatest temperature gradient located on the sample edge area in the scanning direction changes. The maximum temperature in the simulation results and literature experimental results for comparison are in good agreement.