Because of the ultra-high softening point and extremely low thermal expansion coefficient of high borosilicate fireproof glass, it creates a great challenge for tempering. With the flatness guaranteed, high borosilicate glass must meet the requirement for tempering stress and fragmentation specifications. In general, the internal tensile stress is proportional to the compressive stress on the surface . The greater the compressive stress on the surface of the fireproof glass, the greater the internal tensile stress. The greater the tensile stress per unit area, the easier the glass may break spontaneously. Therefore, in order to reduce the risk of spontaneous explosion, we have to reduce the tensile stress around the edge while increasing the surface compressive stress.