In this paper, the finite element simulation model of the electrode melting drops coating process on the workpiece was established, and the numerical simulation of the the temperature field and thermal stress field of the single-pulse electric spark discharge strengthening region was carried out. The results indicated that, in the initial moment of spark discharge, the heat-affected region was small, but the temperature gradient and the maximum temperature were very big. With time increased, heat-affected region kept growing, while the temperature gradient and the maximum temperature both kept decreasing. The extrusion stress mainly concentrated in the region of the outer edge of the combination area of the coating point and the workpiece, and the region of the coating point surface. The tensile stress mainly concentrated in the region of the combination area of the coating point and the workpiece. As time increased, both maximum stress and stress gradient kept growing. The results showed that the experimental data by X-ray stress test had good agreement with the simulation results.