Polyvinyl chloride is high molecular compounds polymerized by vinyl chloride monomer(VCM) with structural element as CH2-CHCLn,degree of polymerization usually as 590-1500.In the process of re-polymerization ,affected by kinds of factors such as the polymerization process, reaction conditions, reactant composition, additives etc.it can produce eight different types of PVC resin performance is different. According to residual content of vinyl chloride in polyvinyl chloride resin, is can be divided into :commercial grade, food hygiene grade and medical application grade in appearance, polyvinyl chloride resin is white powder or pellet