Polyvinyl chloride is one of the most widely used polymeric materials. This polymer has unique properties such as excellent mechanical properties, high chemical and environmental resistance as wll as cost-effectiveness that give it a special role. These properties can be improved by changes in components and structure. One of these changes is the replacement of a percentage of hydrogen atoms with chlorine in the polymer chains and the production of chlorinated polyvinyl chloride, which results in higher thermal resistance than the primary polymer. In this project different methods of polyvinyl carbide chlorination were studied and then according to the possibilities, the process of chlorination was carried out. For this purpose, a suspension of the polymer was prepared in chlorine paraffin and then at a temperature of between 80 and 120 chlorination processes. Then the product was analyzed by elemental analysis after removal of chlorinated paraffin. IR spectra of the product were also prepared for evaluation. The results showed that a polymer with about 63% chlorine had been prepared.‎