A composite for manufacturing a barrier layer, a barrier layer, a method for manufacturing the barrier layer, and a packaging material are provided. Based on the total mass of the composite as 100 parts by mass, the composite includes the following components by mass: Polyhydroxyalkanoate, 70 to 96 parts by mass; polylactic acid, 1 to 15 parts by mass; modified layered silicate, 1 to 5 parts by mass; polyalkylene carbonate, 1 to 20 parts by mass; and auxiliary agent, 1.3 to 12 parts by mass.