Plastic packing bag is a kind of plastic raw materials, packaging bags for various products in the production and life, is widely used in daily life and industrial production, but this was a convenient but lasting harm. Plastic bags used for polyethylene films made from the film, non-toxic, so that it can be used for food. There is also a film made of polyvinyl chloride, polyvinyl chloride itself is non-toxic, but the use of the film by adding additives are often harmful substances, with a certain toxicity. So this type of film and plastic bags made by the film are not suitable for holding food.