The process of solid boronizing and laser surface treatment is applied to getting boron eutectic layer for purpose of lowering samples'crisp property; The microstructure is observed by using SEM, optics microscope, Fe - B-C equilibrium diagram, the mechanism of boron eutectic and behavior of layer is discussed in the course of laser treatment. In virtue of three-dimension thermal-conducting partial differential equations, it proves that the parameters of treatment are reasonable. With solid boronized and laser surface treatment on 45 steel, the layer with appropriate tenacity and hardness can be obtained.