It is prepared via special processes. The diameter of the graphene nanofiber can be adjusted within a broad range featuring a minimum of 10 nm. It can be prepared at a mass-production level. The surface of the nanofiber is decorated with vertical graphene sheets with heights of several nanometers. It has high surface reactivity and large specific surface area (1000 m2/g). Applications: supercapacitors, lithium ion batteries, adsorption and purification, catalysts and catalyst carriers, etc.