Abstract: The casting process of main bearing pedestal used in drilling pump was simulated and optimized.The casting 3D model was built by using UG software, the solidification process of the casting was numerically simulated by using ProCAST software, and slice analysis of casting defects was carried out. The results show that using horizontal pouring casting method and big module exothermic riser, the feeding amount of molten steel in the hot spot is increased. At the same time, the external cold iron is placed at the far end of the riser to make the casting solidify sequentially. The shrinkage cavity and porosity in the key area of the casting are eliminated successfully by using the optimized process scheme.