In order to meet the calibration needs of large?size transient pressure probe rakes, a pressure probe rake calibration method based on expansion shock tube was proposed. The FLUENT software was used to simulate the dynamics of the shock wave in the shock tube, and the operation law of the shock wave and the change of pressure and density of the flow field were analyzed. The results showed that the pressure in the low?pressure section eventually became uniform after being affected by the incident shock wave, the reflected shock wave, the compression wave and its multiple reflections. The pressure measurement experiments were conducted by using the expansion shock tube device with soft and hard aluminum diaphragms. The results showed that the rise time was less than 9 ms and the duration of platform pressure was greater than 50 ms in the low?pressure section inside a 150 mm diameter of shock tube. This study has important reference value for the calibration of transient pressure testing systems in aero engine, aerospace, medical and other fields.