Abstract: Low pressure and vacuum discharge of satellites is induced by environmental factors. The caused hazards cannot be eliminated so that the risks cannot be avoided. A safety design method based on the fault causation theory was proposed in this article. It is to explore various causes of fault phenomena aiming to solve the main problems encountered. The safety elements and risks of each discharge protection design were deeply analyzed in order to formulate effective measures to prevent the risks. Finally, taking a specific satellite as an example, statistical analysis, engineering analysis, and mathematical analysis were used to investigate the causes of low pressure and vacuum discharge for satellites. Meanwhile, the risk pre-evaluation in addition to control measure design and verification were carried out. It is demonstrated that the proposed method is effective and feasible.