Abstract: The regenerator filled with solid matrix is one of the major components in the PTC (pulse tube cryocooler). In this paper, a new source/sink model instead of porous medium assumption, which is merely applicable for low frequency apparatus, is established to simulate the flow and transport in the regenerator. The new model also is a non-thermal equilibrium model. Based on some assumptions, the analytic solution of the filled solid temperature can be obtained. The new model can reduce the computational workload because the model does not require the establishment of the energy equation of solid. We also propose a method to calculate the value of convective heat transfer coefficient under the alternating flow conditions. According to the comparison with the experimental data, the new model is verified. Then the model is used to analyze the heat transfer mechanism between the working fluids and the solid fillers in the regenerator.The regenerator heat transfer performance are optimized under different mesh screen geometries and properties with numerical simulation.