In order to achieve the features of miniaturized intelligence and reliability in high overload environments for small-caliber detonators, a silicon-based electrothermal MEMS safety mechanism was designed. This mechanism is capable of identifying launch environments and reliably operating under high overload conditions. It employs a triple safety lock mechanism for secure unlocking. The design of the MEMS safety mechanism was tailored to the launch information of small-caliber detonators. ANSYS was used to conduct reliability simulations for the recoil threshold mechanism of the cantilever beam and the centrifugal locking mechanism. Additionally, the reliability of the electrothermal actuator was verified through multiphysics coupling analysis using COMSOL software. Through these simulations and analyses, the reliability of the MEMS safety mechanism was validated. The electrothermal MEMS safety mechanism offers the advantages of being miniaturized, intelligent, and capable of reliable operation in high overload environments. The thorough simulation and analysis processes ensure the performance and reliability of the mechanism in real-world applications.