The invention discloses a method for preparing a carbon nanowire/amorphous carbon composite membrane through a reaction magnetron sputtering deposition technology. A monometal target with a catalyticeffect serves as a sputtering target material, methane-argon mixed gas serves as a reaction gas source, and the nano-composite structure containing composite membrane with the carbon nanowire arrays embedded to the amorphous carbon membrane is obtained through an in-situ self-forming method. The composite membrane has excellent mechanical performance and meanwhile has good field emission performance and flexibility, and huge potential application prospects are achieved in the field of flexible electronic devices. The carbon nanowire structure is self-formed in the amorphous carbon membrane insitu through a one-step sedimentation method, the preparation process of the method is simple, membrane forming is uniform, repeatability is good, the energy consumption cost is low, and the carbon nanowire/amorphous carbon composite membrane is especially suitable for continuously preparing flexible field emission electronic devices on a large scale in industrial production.