The fracture splitting notch is processed by NdYAG pulse laser on the material of engine crankcase bearing bracket. The result shows that, the organization of laser heat-affected zone is refined, the melting zone produces the dendritic primary crystal and the ledeburite, the transformation hardening zone obtains hidden needle martensite and the retained austenite. The analysis of X-ray diffraction (XRD) indicates that the carbon density of the melting area is bigger than that of the transformation hardening zone. The micro hardness of the region nearby the fracture splitting notch is higher than that of the parent metal, the hardened effect is obvious and the micro hardness of the melting zone is approximately 260 HV higher than that of the transformation hardening zone. The hardening layer of the fracture splitting notch increases as the pulse power and the pulse width of laser increase, and reduces as the laser scanning speed increases. The depth of the hardening layer is between 0.232～0.625 mm. The fracture splitting notch that is processed by laser is the straight gap, which is a significant effect on the initiation fracture and fracture splitting of the gray iron. The influence law that laser power, pulse width, processing speed and other parameters on the morphology of fracture splitting notch is concluded, and the proposal to technological parameter′s choice is put forward.