Cationic polymers are an important class of functional polymer has a high value in the field of textiles, paper, petrochemical, water treatment, pharmaceutical preparations, and daily chemical. Cationic polymers include quaternary ammonium salt polymers, and quaternary phosphonium salt polymers, and quaternary sulfonium salt polymer. Which most studied and most widely used, most product categories is a quaternary ammonium salt polymer, can be prepared by quaternary ammonium cationic monomer polymerization or monomer graft modified natural polymers. Quaternary ammonium salt type cationic monomer have many types, mainly contain diallyl quaternary ammonium salt, methyl acrylate, or amide quaternary ammonium derivatives, tertiary amine derivatives and vinyl pyridine. Diallyldimethylammonium chloride, abbreviated as DMDAAC) as a quaternary ammonium cationic monomer, can be seen as a function of specific intermediates can participate in the homopolymerization and copolymerization systemcationic polymers. Its homopolymer and copolymer has the advantages of high charge density and adjustable, good water solubility, relative molecular mass regulation, cationic structural units stable and efficient non-toxic on macromolecular chains. It is widely used in the field of oil exploration, textile printing and dyeing, paper, daily chemical and water treatment, especially in oily wastewater, eutrophication and algae micro-polluted water treatment, particularly noteworthy. The methods of prepared monomer the DMDAAC contain one-step and two-step. One-step process reaction is carried out in an aqueous solution, the process is simple, less waste, the monomer product yields (> 90%), because of unreacted raw materials, intermediates, and byproducts, and other impurities, only suitable for use as industrial raw materials. Two-step process of the two-step reaction is carried out in an organic solvent, in steps, to give monomer fewer impurities, but the process using an organic solvent and excess base, resulting in waste, high production costs, a low yield (<68%), generally only suitable for laboratory synthesis. The initiator of synthesis PDMDAAC are usually a water-soluble azo and peroxide initiators. The former lead to high efficiency by the media impact is small, but the low level of commercialization, the price is high, sources is limited, although in the latter triggered the process by the media and impurities affect large, but its wide range of sources, stable, suitable for industrial production. Therefore, by the one-step monomer as raw materials, stable inorganic peroxides as initiator through process research a preparation with a higher relative molecular mass PDMDAAC product of the industrial system of law, has been one of the research directions in the field. Industrial one - step monomer DMDAAC solution as the raw material, and ammonium persulfate as the initiator, and the initiator is added in one gradient heating, step initiator of polymerization method can be prepared by the characteristic high viscosity PDMDAAC product, this method can be a high degree of industrialization. Meanwhile, as the water-soluble polyelectrolytes, different relative madman quality PDMDAAC of a different nature, properties and uses.The process and mechanism to obtain high relative molecular mass PDMDAAC is more, However, the method by controlling the polymerization reaction conditions with the serialization and the relative molecular mass adjustable PDMDAAC few studies.