Abstract: Based on two-dimensional CFD numerical calculation, the simulation of a 6W@80K coaxial stirling type pulse tube refrigerator was carried out. The performance of the whole machine under different running frequency and charge pressure was studied. It is found that the refrigeration coefficient increases first and then decreases with the increase of running frequency. And with the increase of charge pressure, the refrigeration coefficient also increases. The internal flow state of the pulse tube was studied. It is found that the gas in the pulse tube presents the reciprocating oscillating state in the axial direction. When the direction of the gas in the pulse tube changes, vortex will be generated in the hot and cold end of the pulse tube, and the vortex size changes little under different charging pressures but decreases with the increase of running frequency. The two-dimensional simulation results were compared with the one-dimensional simulation results and experimental results. The results show that when the input power of the two-dimensional CFD numerical model is large, the calculation result of the refrigerating capacity of the whole machine is more accurate.