Plastic is used for various purposes in everyday and industrial fields, and has excellent characteristics such as corrosion resistance and insulation. Plastic production is increasing every year, and waste plastics generated accordingly need to be treatment. Currently reclamation and incineration are used as waste plastics treatment methods, but secondary environmental pollution causes ground instability or emission of HCl and dioxin, so research on proper treatment and recycling is required. Therefore, polypropylene and polyethylene which account for a high proportion in waste plastic were used as samples in this study, the composition and pyrolysis characteristics of samples were considered through TGA, elemental analysis, and proximate analysis. In addition, activation energy according to the heating rate was derived using kinetic analysis based on TGA data, and pyrolysis was performed in the fixed bed reactor with the reaction temperature and heating rate as parameters. The yield was measured based on the mass change of solids and liquid products before and after pyrolysis, and we accordingly investigated the optimal reaction temperature and heating rate at which the highest yield can be obtained.