Abstract: The end-window Geiger-Müller counter (end-window G-M counter) is one of the key front-end detection components in radiation detection equipment such as radioactive surface contamination monitors, which belongs to the electronic vacuum devices. In order to solve the problem of the ultra-thin window of end-window G-M counter being easily damaged due to high stress during high vacuum packaging process, the construction of a finite element numerical simulation model for the counter based on material constitutive models such as linear elastic model and elastoplastic model has been completed. The stress-deformation distribution and failure behavior of the window structure under vacuum conditions were analyzed, the mechanism and law of the damage effect of the window were clarified, and the damage threshold of different window structures and materials were summarized. Meanwhile, a new approach was proposed for efficient and stable vacuum packaging of the counter. The research results indicate that for large-area mica windows with an effective diameter of 44.5 mm and a thickness of 5-7 μm, the pressure difference inside and outside the window should be controlled within 12 750-16 000 Pa during the packaging process, and the axial deformation displacement should not exceed 2.694 mm. As the thickness of the mica window increases, its pressure bearing capacity significantly improves. When the thickness of the mica window is 53 μm, the window can withstand a pressure difference of 101 325 Pa (standard atmospheric pressure) without damage. For windows of the same thickness and material, the pressure bearing capacity of small area windows is better than that of large area windows. Among the three materials of mica, beryllium, and titanium, the beryllium window has the worst pressure bearing capacity, while the titanium window has the best pressure bearing capacity. Adding a certain thickness of reinforcement material to the surface of the window can greatly enhance its pressure bearing capacity. If the reinforcement material is selected appropriately, the removal of the material will not affect the original structure and working performance of the counter. The reinforcement materials that meet the requirements include some metal materials, salt crystals, adhesive materials, etc. Taking aluminum as an example of metal reinforcement material, when a 15 μm thick aluminum film is added to the window, the window can withstand a pressure difference of 101 325 Pa without damage. Meanwhile, the aluminum film can be completely dissolved by sodium hydroxide solution, and the dissolution process will not cause damage to other components of the counter. The relevant numerical models, analytical methods, and simulation data can guide the design of the core vacuum system in the production process platform for end-window G-M counters, the setting of key process parameters, and the implementation of vacuum packaging processes. This approach also holds instructive significance for the design and fabrication of other end-window-type gas radiation detectors. The proposed reinforced end-window vacuum packaging technology theoretically prevents accidental damage to the end-window during end-window G-M counters preparation caused by human errors, aging of vacuum control components, or algorithm strategy failures, thereby improving production yield.