Problems of the “false closure” and “instant closure” affect the antijamming capability and reliability of the micro-switch. Based on the sticking action, a new bistable micro-switch is put forward. A sine model is presented to describe the random distribution of the MEMS rough surface. Based on the sine rough model, the Casimir adhesion is simulated. The electric field force, which includes the edge effect, is discussed. Finally the threshold structure size is obtained, which can control the micro-switch to close stably and trigger automatically.