Abstract: With the continuous development of MEMS technology, higher requirements are put forward for the reliability of the MEMS safety system in the fuze. In order to solve the problem of incomplete reliability data of various institutions and depending mainly on a large number of experiments or expert experience in the current MEMS safety and reliability analysis, in this paper, analyzing the failure status of the MEMS safety system, a fault tree of the MEMS safety system was constructed and the reliability function of each key organization was calculated. Based on this, a reliability analysis method was proposed, transforming fault tree and Bayesian network. At the same time, the probability importance and structural importance were calculated for each failure mechanism, and the key optimization mechanism in the design of MEMS safety system was proposed from the perspective of reliability importance, and some calculation example analyses were carried out. Based on the MEMS processing technology, a MEMS safety system was produced, and the reliability experiment was carried out, proving the rapidity and accuracy of the calculation of this method.