For studying the heating phenomenon in the gas dynamic resonance tube, the two dimensional axisymmetrical Euler equations and the explicit MacCormak scheme were used to simulate the non-stationary flow field in a resonance tube. Calculations were done for the driving gas of different pressures. Pressure oscillating histories and distributions of other flow parameters in the resonance tube were obtained. The calculated results confirm that the inflow and outflow of traveling shock waves and expansion waves by turns in the resonance tube results in the pressure oscillation, and the pressure oscillation is related to the pressure of the driving gas. Agreement of the calculated pressure oscillating curves with experimental results suggests that the employed numerical method is valid in modeling the resonance flow process.