In this investigation for Expandable Pattern Casting (EPC) simulation, an algorithm was developed to calculate the gas pressure of the evaporated foam during mould filling. Also, the effect of backpressure evaporative foam on filling behavior was modeled with a new experimental function by adding a Volume of Fraction (VOF) function. The simulation of molten flow and track free surfaces is based on the (Solution Algorithm) SOLA-VOF numerical technique. To simulate the three-dimensional incompressible flow of melt in EPC moulds, the pressure boundary conditions, heat transfer and foam gas pressure effect were modified. In order to verify the computational results of simulation melt flow in EPC casting, a thin grey iron plate was poured into a transparent foam mould. Mould .filling and foam depolymerization were recorded with a 16mm high-speed camera. The comparison of experimental and simulation results of the sequence filling of EPC casting showed a good consistency, which confirms the accuracy of the model.