Expanded polystyrene boards are produced by blending resin with polymer, injecting a catalyst during the heating process, and then extruding continuous closed-cell foam plastic boards. These boards feature an independent, sealed bubble structure within, and are an environmentally friendly thermal insulation material with excellent properties, including high compressive strength, low water absorption, moisture resistance, airtightness, lightweight, corrosion resistance, and ultra-anti-aging (virtually no aging with long-term use), as well as low thermal conductivity.