For the sake of solving the problem of surface wear and failure of the hot work die, based on ANSYS APDL software, a Gaussian heat source was applied to the hot work die by numerical simulation, and the H13 alloy powder was clad by the life and death element method. The process parameters were optimized and selected through the temperature field and stress field. The optimized process parameters were tested and verified, and the performance of the coating was tested. The results show that the optimal simulation parameters within the selected parameter range are the laser power of 1200 W and the scanning speed of 12 mm/s. The simulation results are close to the morphology and temperature distribution of the actual coating. The heat-affected zone in the numerical simulation and the combination of the results are highly consistent with the experimentally prepared results; the measured depth of the cladding layer is 0.13 mm, which corresponds to the simulated depth of 0 mm~0.2 mm, which further illustrates the reliability of the simulation results; the hardness and wear resistance of the cladding layer have been greatly improved, which are 3 times and 28 times more than that of the matrix, respectively. The results of this study provide a reference for strengthening and repairing hot work molds.