The interpenetrating network structure polymer plastic alloy formed by blending modified PVA and modified starch is biodegradable. Films suitable for food packaging, agricultural water-soluble films, containers and disposable consumer products are often produced. The waste can be swallowed by microorganisms in moist soil and degrade into carbon dioxide and water, which is non-polluting to the environment and beneficial to the environment. Environmental protection and realization of green consumption, so the products prepared are environmentally friendly products with good application prospects.