Abstract: To study the fast-pressure-relief effect, a novel mechanical facility capable of instantaneous depressurizing is designed for large-sized pressure relief openings, and the related kinetic and dynamic modeling studies are carried out. The mechanism consists of a spring-based energy storage mechanism, a connecting rod-type latching mechanism, an SEA-based locking/releasing mechanism, and an inertia wheel-based electromagnetic buffer mechanism. It enjoys several advantages like the easy maneuverability, the repeatable usage, and the high testing efficiency. The finally designed fast-pressure-relief mechanism can enable a 750 mm diameter pressure relief door to shift from 0° to 90° position within 280 ms. This work provides some theoretical basis and technical support for the development of the large-sized pressure relief environmental simulation equipment in the future.