To improve the shock reliability of the MEMS inertial switch, a flexible stop structure was proposed. Firstly, the stop collision model was established using the theory of continuous contact force, and the response characteristics of the switch in different stop modes were researched conducting simulation on the model through Simulink. Then, from the perspectives of space-efficient and the stress concentration, the cantilever type and plane micro-spring type stops were discussed and the stop structure was designed. Finally, the switch prototypes were fabricated using the UV-LIGA technology, and the prototypes were tested by the drop hammer shock system. Collision contact force was critical for shock reliability, Simulink simulation result shows that the flexible stop structure can greatly prolong the collision contact time, thus reducing the contact force. At the same time, it also improves the contact bounce phenomenon using flexible stop after collision and the stability of latching. The shock test shows that the cumulative failure distribution function (CDF) of the switch accords with Weibull distribution, with scale parameter (reference acceleration) α=29 600, shape parameter β=8.2. Compared with the MEMS switch without flexible stop, the proposed flexible stop improves the shock resistance of the switch significantly. Modeling, simulation and test of flexible stop provide beneficial reference resources for anti-shock design of MEMS inertial switch.