Polyolefin film for express bubble bag and preparation method thereof

A polyolefin film for an express bubble bag comprises a surface layer, a middle layer and an inner layer which are sequentially arranged from top to bottom, the inner layer is compounded with a bubblefilm, and the polyolefin film is prepared from the following components in parts by weight: 100 parts of high-pressure polyethylene LDPE, 100-200 parts of linear polyethylene LLDPE, 80-150 parts of metallocene polyethylene MPE and 1-2 parts of a processing aid; the middle layer is prepared from the following components in parts by weight: 100 parts of low-pressure polyethylene HDPE, 50-100 partsof homo-polypropylene, 40-80 parts of metallocene polyethylene MPE and 1-3 parts of a processing aid; and the surface layer comprises the following components: 100 parts of low-pressure polyethylene HDPE, 50-150 parts of co-polypropylene and 1-2 parts of a processing aid. The polypropylene is added into the middle layer and the surface layer of the polyolefin film, so that the stiffness, the temperature resistance and the