A synthetic hydrated aluminosilicate (zeolite) or natural zeolite with the function of screening molecules. Its general chemical formula is (M'2M)O·Al2O3·xSiO2·yH2O, and M'and M are respectively monovalent and divalent cations such as K+, Na+ and Ca2+, Ba2+, etc. It has many pores with uniform pore size and neatly arranged pores in its structure. Molecular sieves with different pore sizes separate molecules of different sizes and shapes. According to the different molecular ratios of SiO2 and Al2O3, molecular sieves with different pore sizes can be obtained. Its models are: 3A (potassium A type), 4A (sodium A type), 5A (calcium A type), 10Z (calcium Z type), 13Z (sodium Z type), Y (sodium Y type), sodium mordenite type Wait.