The utility model provides a superspeed mechanical switch and a switch fracture thereof. The switch fracture comprises two conductive terminals and two differential plate sets arranged between the two conductive terminals. Each differential plate set includes one or more than two insulating plugging plates that are staggered and plugged mutually; conducting elements that can be staggered mutually or can be arranged into one row to realize conduction of the two conductive terminals are arranged at the insulating plugging plates of the two differential plate sets. Insulating guiding blocks are arranged at the front sides of the conductive terminals at the opening direction and have guiding surfaces that can guide the insulating plugging plates to move at the opening or closing direction and limit the insulating plugging plates to move at the direction perpendicular to the opening or closing direction. When the switch fracture is used, the side surfaces of the insulating plugging plates are contacted and guided by the guiding surfaces, so that the insulating plugging plates can be prevented from vibrating or deformation at the direction perpendicular to the plate surface; the plugging stability and precision of the two differential plate sets are improved during the opening and closing motions of the insulating plugging plates, so that the insulating plugging plates can be protected effectively from being damaged and thus the service life of the switch fracture is improved.