Laser fracture splitting technology significantly improves the processing quality and efficiency of engine crankcase main bearing block. In order to research the splitting mechanism of ductile iron material fracture notch cauterized by Nd: YAG Laser, the FEAmodel of fracture splitting processing of engine crankcase main bearing block has been developed successfully. The splitting parameters of ductile iron material (QT500-7) main bearing block is analyzed. The numerical simulation results indicate that: among all the key parameters affecting the quality of fracture splitting, the effect of notch depth on fracture splitting load is more obvious than that of the notch opening angle and radius. The value of splitting load decreases rapidly with the increasing notch depth, while the splitting load increases with the increasing notch angle and radius. The optimum value of the notch depth, angle, and radius should be respectively at 0.5 mm, 60 o, and 0.2 mm. The results have been proved by experiments. The optimum parameters obtained from the ABAQUS simulation and experiments provide a numerical reference for significantly reducing the splitting load and optimizing the fracture splitting process, help to achieve the rapid development of engine block process and promote the green manufacture of automobile industry.