The invention relates to a compression-resistant buffer packaging bag and a preparation method thereof. The packaging bag is formed by heat sealing of a composite film; a heat sealing area of a packaging bag body comprises a false sealing area body and a true sealing area body which are arranged in parallel; the false sealing area body and the true sealing area body are sequentially arranged fromthe inner side to the outer side of the packaging bag body; the heat sealing strength of the false sealing area body is lower than the heat sealing strength of the true sealing area body; and when theouter ambient atmospheric pressure is decreased after the packaging bag body is inflated and used, the composite film of the false sealing area body is automatically stripped. The preparation methodcomprises the steps that during preparation, a composite layer, a middle layer and an inner layer material are added into an extruder so as to obtain a D-PE blowing film layer through a three-layer co-extrusion mode; then the D-PE blowing film layer and an outer printing film layer are subjected to glue compounding, curing and slitting so as to form the composite film; and finally, heat sealing iscarried out on the composite film through heat sealing blocks so as to form the packaging bag. The prepared composite film and the packaging bag prepared from the composite film can resist the continuous environment differential pressure action force, so that the problem that bag explosion occurs due to the fact that the packaging bag is produced in a high-air-pressure region and enters a low-air-pressure region for sale can be effectively avoided.