Abstract: With a view to the in-orbit lifespan assessment and extension requirements for China’s Space Station, an accelerated life test considering the alternating effects of in-orbit long-term storage and short-term operations was conducted on the switch buttons of extravehicular power tools, employing multiple temperature levels, to investigate their degradation characteristics and failure mechanisms. Meanwhile, a reliability assessment was carried out using a method based on pseudo-life distribution. The accelerated life test results reveal that the switch buttons exhibit pressure relaxation at temperatures of 50 ℃ and 80 ℃, with linear pressure degradation. At temperatures of 110 ℃ and 140 ℃, the switch buttons experience sticking, jamming, and lubricating grease overflow, leading to a significant increase in delayed pressing force in late storage period. The reliability assessment results indicate that the switch buttons meet the specified reliability requirements of 0.995 4 at the end of the 10-year lifespan. The research may provide a reference for the reliability assessment of similar long-term storage units onboard China’s Space Station.