The invention belongs to the technical field of material preparation, and particularly relates to a two-step calendering device for graphite and a calendering method. The calendering device comprisesa main calendering structure, the main calendering structure comprises a graphite unwinding shaft, a cover film unwinding shaft, a main calendering upper roller, a cover film winding shaft, a first release film unwinding shaft and a main calendering lower roller; the calendering device further comprises an additionally-arranged secondary laminating calendering mechanism; the secondary laminating calendering mechanism comprises a secondary laminating calendering upper roller, a graphite winding shaft, a first release film winding shaft, a secondary laminating calendering lower roller, a secondrelease film unwinding shaft and a second servo motor; and the secondary laminating calendering upper roller is installed at the material outlet end of the main calendering structure, the main calendering structure is installed on an installation frame, a gap between the secondary laminating calendering upper roller and the secondary laminating calendering lower roller is controlled by a passing roller and the second servo motor, and the second release film unwinding shaft and the first release film winding shaft are fixedly installed at a material receiving end. The device provided by the invention solves the problems that graphite easily remains on a release film, calendering is insufficient, and the thickness of the graphite does not reach the standard, has a simple structure, and is convenient to use.