With the development of Micro-satellite,the number of satellites launched every year in the world is gradually increasing. As a key technology in micro-satellite,the release device is required as simple and reliable,without the production of redundancy. Of these release device,the pyrotechnic device is the most widely used. To avoid the formation of space trash by the broken hold-down rod,the unlocked rod needs to set the capture cap to limit its movement. So,the strength and structure form of the capture cap directly influence its functions. Based on the non-linear analysis software ABAQUS,the characteristics of the capture cap’s structure and its fixed form are studied and the weak position of the release device is located and verified. The results of simulation and electric explosion tests show that the weak position of the device can withstand the impact after the pyrotechnic release. This method can be applied to aeronautics and astronautics fields,providing an effective way for the analysis of various types of unlocking devices,such as satellite-rocket separation and rocket fairing separation.