Expanded polystyrene boards are made by blending resin with polymers and injecting a catalyst while heating, then extruding them to form continuous closed-cell foam plastic boards with independent sealed bubble structures. These boards feature excellent properties such as high compressive strength, low water absorption, moisture resistance, airtightness, lightweight, corrosion resistance, and ultra-anti-aging (virtually no aging over long-term use) with low thermal conductivity, making them an environmentally friendly thermal insulation material.