Disclosed are an electronic device and the manufacturing method thereof, a manufacturing method of a thin film transistor, and an array substrate and manufacturing method thereof. The manufacturing method of an electronic device includes: forming a metallic structure on a base substrate; forming an oxygen-free insulating layer on the metallic structure and the base substrate; and forming an insulating protective layer on the oxygen-free insulating layer. The manufacturing method of the electronic device protects a metallic structure by forming an oxygen-free insulating layer, not containing oxygen elements, on the metallic structure, and hence prevents the metallic structure from being oxidized.