PH value 12, density 1. 18 ~ 1.2, and solid content ≥ 20%. It is sprayed on the surface of dry porous inorganic building materials such as brick, cement, stone, gypsum, lime, fangci paint, asbestos products, perlite and insulation board. Very active nano-silicon particles penetrate into the interior of building materials, cross-linking to form a solid network crystal structure, blocking pores and forming a colorless permanent waterproof layer; At the same time, silane-based components are consolidated on the surface of building materials to produce strong hydrophobic molecules, which have excellent waterproof and impermeability. It can effectively prevent buildings from weathering and frost cracking, and has the functions of cleaning, anti-fouling, anti-mildew and anti-moss. Nano-silicon waterproofing agent is directly mixed into cement mortar or concrete, which is used for self-waterproofing projects of rigid structures such as pools, dams, culverts, toilets, bathrooms and basements. Its unique waterproof effect can be seen. Nano-silicon waterproof agent has reliable quality, good durability, acid and alkali resistance, excellent weather resistance, no corrosion to steel bars, safe use, convenient construction and low cost, and is one of the ideal waterproof materials in building engineering. Its impermeability in mortar is ≥S 14 and in concrete is ≥S 18. The technical indicators meet the standards of JC 474- 1999[ Waterproofing agent for mortar concrete] and JC/T902-2002[ Permeable crystallization waterproofing agent].