Expanded polystyrene boards are produced by mixing resin with polymers, injecting a catalyst during the heating process, and then extruding them into continuous, closed-cell foam plastic boards. These boards feature an independent, sealed bubble structure. They are an environmentally friendly thermal insulation material with excellent properties such as high compressive strength, low water absorption, moisture resistance, airtightness, light weight, corrosion resistance, and ultra-anti-aging (virtually no aging after long-term use) with a low thermal conductivity coefficient.