Abstract: stopper can be used for shock protection, however, traditional stopper may generate secondary shock which could result in fracture, debris, and performance shifts of the device. The problem can be efficiently solved by introducing elastic stopper, but its protective effect is greatly influenced by stoppers parameters. In order to get the best parameter, impact dynamic model of MEMS is established at first, based on which the factors affecting shock response are extracted. Then the parameters of elastic stopper, including elastic coefficient and limit distance are emphatically analyzed, the method of designing elastic stopper and final result are finally provided. Results show that: effective shock protection must minimize the motion of microstructure as well as maximize buffer performance. Besides, minimizing limit distance is also helpful to improve anti-shock ability.