The physical gap is a kind of security protection products that can guarantee information security by disconnecting the connections between the intranet and the extranet. It’s commonly deployed between the secret-related network and the Internet to protect information security. Because of the market demand, a lot of gaps are produced, but without strict quality control. However, the importance of the physical gap’s quality and stability continue to grow with the intensification of competition in the marketplace. In addition physical gaps may exhibit failures or degrade only under certain stress conditions in most cases. So it’s necessary to conduct test especially stress test for the physical gap. In fact, the most effective way to qualify a physical gap and to assure whether a physical gap meets its stability and quality goals is through stress testing. In this paper, we discuss why and how to qualify a physical gap through stress testing. We also presented a stress testing case designed for the physical gap to show how to conduct stress testing and analyze the testing result. To the best of our knowledge, there is a lack of research about conducting stress test for physical gap to date.