In lost foam casting (LFC), the foam pattern is the key qualification, and the filling process is one of the crucial processes to ensure the high quality of the foam pattern. Filling without uniformity and denseness will cause various defects and affect the quality of the surface. The influential factors of filling process are analyzed .And optimizing filling process, enhancing efficiency, decreasing waster are obtained by the numerical simulation of filling process using computer. The governing equations of the dense compressible gas-solid two-phase flow are established, and the physical signification of each one in the equations is discussed. The filling process is solved by Euler- Euler model. In the simulation, the volume of foam bead in every governing unit at different time is calculated, and the trend of foam bead flow is obtained. The filling process of various different conditions is simulated, considering different shooting methods and the position of baffles, and recorded by digital vidicon. The characteristics and the rules of the process are summarized. By contrasting the result of the numerical simulation with the one of examination, it is found that the fluid trend of foam bead in the numerical simulation is accordant to the actual process. So the numerical simulation of filling process by applying this model is an effective method.