Extruded polystyrene foam board, referred to as extruded board, also known as XPS board. The XPS board is made of polystyrene resin supplemented by polymer. While heating and mixing, the catalyst (such as freon, butane and carbon dioxide CO2, etc.) is injected, and then the continuous closed-cell foamed rigid foam board is extruded. The hard film formed on the surface is uniform and flat, and the inside is an independent closed bubble structure.