Abstract: The present disclosure discloses a composite layer and a method for manufacturing the same, and an OLED device comprising the composite layer. The composite layer comprises a planarization layer and an anode layer that is connected with the planarization layer, wherein the planarization layer is made of a composite material comprising polymethylmethacrylate and a nanoparticle, and the nanoparticle is a silicon dioxide, titanium dioxide, aluminium oxide or zinc oxide nanoparticle. The method for manufacturing the composite layer comprises: obtaining a composite material comprising polymethylmethacrylate and a nanoparticle by reacting a sol of the nanoparticle or a nanoparticle surface-modified by a silane coupling agent with methylmethacrylate; obtaining a planarization layer by spin coating, exposing and developing the composite material; and obtaining a composite layer by forming an anode layer on the planarization layer.