Brief introduction The rare-earth elements (REE) are the elements Sc (scandium) Y (yttrium) and the 15 lanthanide elements with atomic numbers 57 through 71, namely, La (lanthanum), Ce (cerium), Pr (praseodymium), Nd (neodymium), Pm (promethium), Sm (samarium), Eu (europium), Gd (gadolinium), Tb (terbium), Dy (dysprosium), Ho (holmium), Er (erbium), Tm (thulium), Yb (ytterbium), and Lu (lutetium). The application of rare-earth In the traditional industrial field, rare-earth is mainly used in agriculture, metallurgy, petrochemical industry, glass, ceramics and electric light industry. With the research of rare-earth developing, rare-earth is gradually applied in high and new technology industry, used as luminescent material in display, magnetic material, hydrogen storage material, laser material, high temperature superconducting material, fine ceramic and catalyst. The application of rare-earth in automotive exhaust gas With the growth of automotive quantity, the exhaust emission becomes the flowing resource of pollution, which is a serious harm for atmosphere. To deal with the emission exhaust, we generally adopt to fit purifying equipment. The key of the purifying equipment is catalyst. At present, the widely used catalyst is normally composed by noble metal Pd, Pt, Rh. Though this kind of catalyst posses the advantage of high activity, favorable thermal stability, long service life, its cost is expensive. Since put forward of using catalyst with rare-earth in purifying off-gas, its own catalytic capability has attracted all catalyst researchers’ attention. Such kind catalyst has high activity, favorable thermal stability, long service life as noble metal catalyst; and the rare-earth can improve the activity of catalyst, storage and release the oxide, resist the lead poisoning, furthermore, this kind catalyst is not expensive.. Our company freshly have successfully explored rare-earth complex catalyst, which is a reasonable formula of rare-earth and zirconic oxide. Its particulate is limited about one micron. Because the fine structure of the coat has been controlled, deformation of alumina in high temperature, dispersibility of the noble metal, agglomeration of the noble metal particulate’s deformation have been improved greatly. With the rare-earth complex catalyst, the catalytic converter can reach Euro3 and Euro4 emission standard, meanwhile, the quantity of noble metal is decreased, which evidently reduce the cost for company. In addition, rare-earth complex catalyst has other advantages as follows: (1) avoid the atmosphere pollution of NOx due to the traditional progress of sintering the rare-earth nitrate. (2)simplify the coat technics. (3) raise the conversion temperature of r-alumina to α-alumina Except for purifying off-gas, rare-earth complex material is also applied to deal with industrial exhaust gas and purify the indoor air.