Fumed silica is the superfine micro-nano fine chemical product, which is divided into hydrophilic type and hydrophobic type in accordance with their different surface treatments. Its appearance is white powder. Native particle size ranges from 5nm to 40nm, with significant functions of thixotropy, reinforcing, thickening and filling. Therefore, it is widely used in the industries of rubber, sealant, plastic, resin, paint, printing ink, papermaking, medicine, cosmetics, food etc.