This　present　invention　discloses　a　polymer/potassium　permanganate　composite　film　obtainable　by　a　process　comprising　the　steps　of　using　silane　coupling　agent　for　surface　treatment　of　potassium　permanganate,　　mixing　0.15-0.75　g　of　modified　potassium　permanganate　with　10-20　g　of　polymers　together　to　obtain　a　mixture,　　and　coating　the　mixture　to　obtain　a　composite　film.　The　composite　film　can　absorb　ethylene　generated　by　fruit,　　thus　extending　fruit　ripening　time,　　keeping　fruit　fresh.　It　can　be　widely　used　as　food　packaging　materials.　The　composite　film　also　has　a　good　oxygen　barrier　property　and　has　a　good　efficiency　to　remove　bacteria.　Therefore　it　can　be　widely　used　in　the　pharmaceutical　industry.　The　preparation　method　is　scientifically　sound,　　simple,　　and　has　high　level　of　operability,　　thus　making　it　possible　for　batch　preparation.