Abstract: The present invention discloses a biodegradable complex oxygen barrier film and its preparation method and application. The biodegradable complex oxygen barrier film disclosed by the present invention is constituted of at least two support layers and a barrier layer which is deposed between each two support layers. The support layer is selected from at least one of the following substances: polylactic acid, poly(butylene succinate), polycaprolactone, poly(adipate-butylene telephthalate), poly(?-hydroxybutyrate) and poly(?-hydroxybutyrate-valerate); the barrier layer which is deposed between the each two support layers is same or different, the barrier layer is selected from any one of the following: poly(propylene carbonate) and nano montmorillonite modified poly(propylene carbonate).