COMSOL Multiphysics software was used for simulation of heat transfer in a heat-sealing process of multilayer polymeric films. In order to improve simulation accuracy, the changes in material properties such as thermal conductivity, specific heat and density with temperature were measured in a wide range of temperature. The temperature at the interface of two sealing films was measured using a very fine thermocouple attached to a high-resolution data acquisition system. The simulation results showed a very good agreement with the experimental measurements in a broad range of temperatures, from below the melting temperature of the sealant to above its melting temperature. In addition, comparison with different models available in literature revealed the importance of considering plastic thermal contact resistance (TCR) models as the boundary condition between the sealing jaws and the external layer. These results show that the simulation, for the first time, can precisely predict the temperature profile at each point of the multilayer film in a heat-sealing process without any required fitting parameter. The obtained results point to the significant potential of this simulation as a powerful tool in predicting the sealing behaviour and in reducing the time and energy required for material selection of a package design.