The preparation methods and functional applications of graphene based flexible film composites were summarized. The preparation methods of graphene based flexible composite films include blending, spin coating, encapsulation, electrostatic self-assembly, fragmentation and recombination, in-situ polymerization, ring opening polymerization, etc. Different modification methods or polymer composites will affect the functional application of the graphene based flexible composite films. The metal modification can be used to prepare the gas sensitive sensors which respond to the specific gas and the negative electrode materials of the lithium ion battery with strong electronic transmission capacity; graphene with polymer composite can be used to prepare enzyme sensors, biosensors, biologically supported films, etc. The different doping methods of graphene based films not only make the graphene films have the properties of metal and polymer, but also is of great significance to the development of electronic devices and optoelectronic devices.