A numerical investigation was carried out to simulate migration of gas and liquid phase LPG（liquefied petroleum gas）in sand pond with different water contents by the developed multiphase mixture flow model in part（Ⅰ）.The three-dimensional propane saturation distribution and non-Darcy flow region in sand were visualized.The variation processes of propane average mass flow rate of outlet with time as propane gas and liquefied propane releases were analyzed，and the general rule of LPG outflow through porous media was obtained.The simulation results showed that LPG infiltration direction was affected significantly by gravity and the position of outlet;pressure drive was crucial for LPG infiltration;the flow about release site and outlet was more active where the non-Darcy effect was obvious.The model was verified by an experiment of LPG vapor infiltration diffusion，and the verification results testified the reliability of the model and numerical modeling.