Abstract: Shock tunnel is a common ground test device used for aerodynamic shape design and optimization of hypersonic vehicles. Based on detonation driven technology, shock tunnel can generate high-temperature and high-pressure driver gas in a short test time (millisecond level) to simulate hypersonic test airflow. The main diaphragm is located between the detonation driver section and the shock tube section in the shock tunnel. During the test, the diaphragm is opened under the detonation impulse pressure. The opening state and falling off state of the diaphragm have a great influence on the air quality in the shock tunnel. At the same time, the diaphragm is also a prerequisite for the formation of shock wave. In the traditional wind tunnel, aluminum diaphragm is used for testing. In the shock tunnel, a diaphragm with stronger pressure bearing capacity is needed. At this time, aluminum diaphragm is no longer applicable, and steel diaphragm is needed. Therefore, it is necessary to research the rupture characteristics of steel diaphragm in a shock tunnel. By comparing the numerical results with the experimental results, it is found that the numerical results are in good agreement with the experimental results, and the calculated results are reliable. Based on the stress-strain model of the diaphragm, a dynamic model of the diaphragm opening was established. According to the CJ detonation theory, the process of the diaphragm rupture was simulated by finite element software, and the mechanism and mechanical characteristics of the diaphragm rupture were analyzed and summarized. The control variable method was used to analyze and study the diaphragm of different thickness and groove length, and the change rule of diaphragm rupture pressure and effective diaphragm rupture time was obtained. In the shock tunnel test, the diaphragm parameters suitable for JF-12 wind tunnel were designed according to the total rupture time of the diaphragm.