The invention discloses a pressure-resistant difficult-to-deform PET (polyethylene terephthalateg)/montmorillonite nanometer composite sheet material, which is prepared from the following raw materials in parts by weight:55 to 60 parts of PET resin, 20 to 21 parts of ethylene acrylic ester, 6 to 8 parts of Na-based montmorillonite, 15 to 18 parts of wheat straw, 10 to 11 parts of glass fiber, 0.7 to 0.9 part of nanometer calcium carbonate, 1.1 to 1.4 parts of nanometer titanium dioxide, 7 to 9 parts of sodium benzoate, 8 to 10 parts of para aminobenzoic acid, 0.3 to 0.5 part of N330 carbon black, 0.1 to 0.2 part of zinc borate, 5 to 7 parts of paraffin and a proper amount of water. The modified Na-based montmorillonite is used as a nucleating agent; the glass fiber is added into the raw materials after the grafting modification, and is matched with other effective auxiliary agents; the prepared composite material has high antibacterial crystallization rate, good barrier property, high mechanical intensity, excellent pressure-resistant performance, high rigidity, great toughness, transparency, non-toxicity, odorless and crushing difficulty, and can be completely applied to packaging of liquid of tea beverages, oil products, carbonate beverages and the like.