Insulating glass is a kind of glass product with a drying air space. It is composed of two or more pieces of glass as effective support and partition and uses a seal around the edges. The glass is partitioned with hollow aluminum alloy bulkhead filled with desiccant or compound seal string, and the cavity layer is filled with dry air or inert gas. The bulkhead and glass are sealed with butyl adhesive before the treatment with polysulfide sealant or structural sealant. Insulating glass can be categorized into two-layer and multilayer insulating glass according to the number of cavities. The former is composed of two pieces of plate glass and one cavity, and the latter is composed of more than two pieces of glass and two or more cavities. The more the number of cavities, the better the thermal and acoustic insulation will be. The two-layer and three-layer insulating glass with two cavities are most widely used.