给出了用有限差分法对金属材料激光相变硬化过程建立的三维数值模型。模型考虑了工件有限尺度、工件材料热物理性质的温度依赖关系、激光处理参数以及对流、辐射造成的表面热损失．根据模型可以得出工件表面和内部任意部位的三维温度分布像，可以预测激光处理的相变层深，并据此优化激光处理参数的选定．通过对一种锆合金的激光相变硬化实验，验证了所得结果与模型理论计算的一致． The three-dimensional numerical model established by the laser phase transformation hardening process of metal materials by finite difference method is given. The model takes into account the finite scale of the workpiece, the temperature dependence of the thermophysical properties of the workpiece material, the laser processing parameters and the heat loss caused by convection and radiation. According to the model, the three-dimensional temperature distribution at any part of the workpiece surface and in the interior can be obtained, which can predict the phase change layer depth of laser processing and optimize the selection of laser processing parameters accordingly. The laser phase-change hardening experiment on a zirconium alloy verifies that the obtained results agree well with the model theoretical calculations.