In this study, 45 steel tensile specimens were hardened by laser during a surface experiment that used different laser power strengths, whereas the ultimate tensile strength of each specimen was obtained during a tensile experiment. These experiments measured the depth and hardness of the hardening layers of the surface areas and logged fracture photographs using a scanning electric microscope (SEM) to perform the fractal analysis. The fracture showed fractal characteristics; therefore, fractal theory was applied to calculate the fractal dimension of the fracture. The conclusive research results show that the sample surface-hardening layer depths and surface hardness can be increased by increasing the laser power, and thus causes the gradual decrease of the ultimate tensile strength and the increase of the fracture fractal dimension. The ultimate tensile strength and the fracture fractal dimension can be characterized for this material type.