Preparation method of bio-based weather-resistant environment-friendly packaging bag

The invention relates to the technical field of environment-friendly bag production, and discloses a preparation method of a bio-based weather-resistant environment-friendly packaging bag, during processing, the mass of added polylactic acid is 50 kg, the mass of added starch is 11 kg, and during primary processing, the rotating speed of a stirrer is 45 circles per minute, and the packaging bag is uniformly stirred by regulating the rotating speed. In the processing process in the step S2, the adding mass of thermoplastic polyurethane is 11.5 kg, polylactic acid is added, production of the environment-friendly plastic bag is facilitated, the lactic acid bacteria are glucose obtained by saccharifying a starch raw material, and the content of the glucose in the starch raw material is reduced; the high-purity lactic acid is prepared by preparing lactic acid from glucose and certain strains through fermentation and then adopting a chemical synthesis method, so that the high-purity lactic acid can be completely de