The invention discloses a graphene film with ultrahigh flexibility and high thermal conductivity and a preparation method of the graphene film. The graphene film is prepared from an ultralarge uniform graphene oxide sheet through steps of solution film-formation, chemical reduction, high-temperature reduction, high-pressure compression and the like. The graphene film is formed through physical crosslinking of macroscopic multi-layer folded graphene with microscale folds, and inter-lamella slippage can be realized, so that the graphene film has ultrahigh flexibility. The graphene lamellar structure of the graphene film is perfect, the lamellas have ultralarge crystalline areas which are about 100 mu m and contain few defects, the structure is compact after high-pressure compression, and the graphene film has ultrahigh electrical conductivity and thermal conductivity. The graphene film with ultrahigh flexibility and high thermal conductivity can be bent repeatedly more than 1,200 times, the elongation at break is 12%-18%, the electrical conductivity is 8,000-10,600 S / cm, the thermal conductivity is 1,800-2,600 W / mK, and the graphene film can be used as a high-flexibility, thermal-conducting and electric-conducting device.