A systematic study of the dynamic simulation of a household refrigerator-freezer with R12 and R134a has been made. Basic analysis method of the dynamic simulation is discussed. New evaporator and condenser models are developed by introducing void fraction. A simplified model of capillary tube can decrease calculation time and guarantee the accuracy. A refined compressor model is set up. The thermal insulation layer of a small-scale refrigerator is treated as a multi-layer thermal system. Proper calculation methods for system simulation are approached, and a software for dynamic simulation of a small-scale refrigeration appliance is developed, which can simulate different working process. Experiments has been done on a household refrigerator-freezer charged with R12 and R134a separately. The result shows that the theoretical model fits the actual system well.