As the use of plastics becomes more common, the generation of waste plastics increases, and soil and air pollution problems are intensifying accordingly. To reduce this problem, the importance of plastic recycling is emphasized, and among them, a chemical recycling method using a pyrolysis process is the most effective in terms of recovering raw materials and reducing waste sources. Among various plastics, polystyrene has the highest monomer yield during pyrolysis and is one of the promising options because it is converted into a monomer with only a simple heat treatment. In this study, pyrolysis of waste EPS, which accounts for a significant amount of polystyrene, was performed using a batch reactor. Also, Temperature and catalyst conditions were diversified to select optimal conditions. As a result of the pyrolysis experiment, when the BaO catalyst was used at 390°C, the generated oil and SM mass showed the maximum value (Oil 33.2g, SM 19.27g), and this was selected as the optimal waste EPS recycling condition.